RNG Series: Un’Goro Edition

EDIT: Thanks to @Old_GuardianHS for reminding me adapt is 3/10 not 3/9. Post fixed.

When I first started this blog in the last quarter of 2015, I wrote a bunch of posts where I tried to quantify RNG in the game, the RNG Series. I guess doing the math became too much work for me, as it appears I have not written one of these in 2016 or 2017. Upon the release of all the Journey to Un’Goro cards yesterday, I felt that this expansion had quite a bit of reduction in randomness. Let’s go in and see look at all the random effect cards, and try to quantify some probabilities.

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Un’Goro RNG ain’t your Old Gods’ RNG


  • Single Adapt (12 cards) = 3/10 = 30%
  • Double Adapt (2 cards) = 1 – (7/10)^2 = 51%
  • Galvadon = 1 – (7/10)^5 = 83%

Single Adapts are easy to calculate, just 3 out of 10 outcomes. For multiple Adapts, the events are independent, meaning each roll will be 3/10. So when Galvadon screws you over by not getting Stealth, that was a 17% chance. It will happen.


  • Hydrologist = 3/5 = 60%
  • Primalfin Lookout = [3/18, 3/14] = [16.7%, 21.4%]
  • Chittering Tunneler = 3/25 = 12%
  • Tortollan Primalist = [3/32, 3/25] = [9.4%, 12%]
  • Free from Amber = 3/30 = 10%
  • Primordial Glyph = 3/32 = 9.4%
  • Servant of Kalimos = 3/36 = 8.3%
  • Stonehill Defender = [3/56, 3/49] = [5.4%, 6.1%]
  • Curious Glimmerroot = 3/59 = 5.1% + Your Brain
  • Hallucination = 3/59 = 5.1%
  • Explore Un’Goro = 3/366 = 0.8%

Discover cards all have a numerator of 3, since you are selecting 1 of 3 picks. The denominator will vary quite a range. Hydrologist has a fairly low RNG, as there will only be 5 Paladin secrets in Standard. While Curious Glimmerroot has an inherent 5.1% of a card, you will likely know what class card is in the opponent’s deck. Also since Discover picks from the pool of Class + Neutral, some cards will vary like Primalfin Lookout for Murlocs, Tortollan Primalist for Spells and Stonehill Defender for Taunts. Explore Un’Goro draws from a pool of Warrior + Neutral cards, giving a 0.8% chance for each card.

Random Card Advantage + Molten Blade

  • Crystalline Oracle = [1/26, 1/1] = [3.8%, 100%]
  • Megafin = 1/19 = 5.3%
  • Molten Blade = 1/23 = 4.3%
  • Elise the Trailblazer = 5/135 = 3.7%
  • Lyra the Sunshard = 1/31 = 3.2%
  • Shimmering Tempest = 1/32 = 3.1%
  • Stampede / Jeweled Macaw = 1/76 = 1.3%

Crystalline Oracle will vary depending on how many cards are left in the deck, so highly variable, but limited in Constructed with repeated cards. Megafin will give a 5.3% chance for each Murloc, and that probability will increase depending on how many cards you get to draw. Stampede and Jeweled Macaw had the probability for a desired Beast plummet after the heavy insertion of Beasts in the new set.



  • Tortollan Forager = Turn 2 – 5 attack minions
  • Arcanologist = Turn 2 – Secret
  • Tol’vir Warden = Turn 5 – 2 1-cost minions
  • Mimic Pod = Turn 3 – Anything

Draw cards always start off with a limited denominator of how many cards are left in a deck. Turn 1 players start with 26 cards, while the Coin player starts with 25 cards in deck. Then you subtract what turn a card can be played on inherent card draw. So, the Tol’vir Warden for example, will likely be drawing cards from the smallest deck pool, on average. Mimic Pod is the most variable of these cards, as there is no limiter on what is drawn, like Thistle Tea. Getting 5-attack guys and Secrets are likely more discriminating than 1-cost minions, but these are all random outcomes of limited probability, given the parameters of 30 card decks.



  • Volatile Elemental = [1/7, 1/1] = [14.3%, 100%]
  • Sulfuras = [1/8, 1/1] = [12.5%, 100%]
  • Volcano
    • Chance of getting hit with no minions = 99.9%
    • Chance of not getting hit with 14 minions on board = 38%

Back in GvG, random damage appeared to be the main mechanic. Surprisingly, there are only 3 cards like this in the expansion. Volatile Elemental will range from 1/1 to 1/7, so that can obviously be modified. The Ragnaros hero power from Sulfuras will include the hero, so that bumps an extra character. Volcano, obviously is highly variable, depending on it’s own randomness and how much stuff is on the board. With an empty board, the chance of a hero dodging 15 shots is 0.0031%, so nary impossible. On a full board of 14 minions and 2 heroes, the chance of something not getting hit once is 38%. Of course, there are more complicated calculations depending on how much health everything has, as a minion with 1 health dying off will increase the odds of everyone else getting hit. Too complicated.



  • Giant Anaconda = [1/10, 1/1] = [10%, 100%]
  • Cruel Dinomancer = varies

Again, we’re not in GvG, when Piloted Shredder dropped off anything. Giant Anaconda at the least has a 10% chance, and this is the highly unlikely scenario of having a hand of 10 5-attack guys. Cruel Dinomancer can be controlled by how much discard you are running. If Clutchmother Zavas was thrown away a lot, she will likely be the most likely outcome of summon, as a 2/2.

The upshot

It’s safe to say that Team 5 took the feedback that bad RNG is bad for the game and competitive Hearthstone. Most of the RNG in Un’Goro is Discover and Adapt, outcomes which have a skill requirement to it. Cards with really wacky RNG outcomes likely won’t be all that good in this set. A card like Stampede is likely a card advantage engine, where you’ll just be looking to get “A Beast” rather than “OP Beasts.”

I think that state of the RNG discussion will focus on the Discover cards, since there will always be variation in a pool of 59 or so cards. Adapt is pretty safe as a mechanic, with the 30% probability floor (not to mention multiple good Adapts).

Elements of Hearthstone RNG: Active Reinforcement

I haven’t written an RNG Series article in a while, so here’s one!

I wrote about Passive Reinforcement before, which was a card adding a card to your hand. Since then, the Discover mechanic came out, which greatly expanded the potential card pool to be discovered. Luckily not much has changed for Active Reinforcement, a term I use for something getting summoned to the board. While some cards like Razorfen Hunter and Silver Hand Knight give you Boars and Squires 100%, a lot of other cards will give you something random.

Game-dependent RNG

These cards do not have a specific percentage, as they are dependent as what is in a deck. Because decks are limited to 30 cards, and often have doubled cards, the RNG of these cards are much lower than that of uncontrolled RNG.

  • Voidcaller – Very low randomness, as the reinforcement has to be a Demon in the hand. Because a hand is 10 cards, the lowest percentage for a minion summon is 10%. There is no RNG at all if there is only 1 demon to play.
  • Alarm-o-Bot / Ancestor’s Call – Both cards have the same RNG, as they will take a minion from the hand to the field.  They have the same 10-100% chance for minion summons.
  • Resurrect – The only card to interact with the “graveyard” in Hearthstone, and depends on what is in your graveyard.
  • Desert Camel / Mad Scientist – These cards could do nothing at all in the Arena, as they depend on what 1-drops and secrets are in your deck.
  • Deathlord / Mindgames – These cards dip into a slightly larger pool of all minions in your/opponent’s deck.

Low randomness

  • Animal Companion – While it is always Huffer, all three companions should have a 33% chance of appearing. They are all cards that are worth more than the 3-mana cost. But I think people want Huffer to come out most of the time.
  • Gelbin Mekkatorque – There is a 25% chance for each invention. Homing Chicken is the only one that helps the player only, while the other 3 have a chance to affect either side of the board. I’d say that the Poutrylizer is worst outcome for a player, so there is a 75% chance of getting something more desirable.

Medium randomness

  • Tuskarr Totemic – There are 8 totems out there, meaning there’s a 12.5% chance for a summon with this card. 4 of the 8 are the “good totems”, the ones that are not the 4 default Shaman totems.
  • Murloc Knight – With 14 Murlocs, there is a 7% for each Murloc. While there is a Murloc generated for each inspire, there are really 5 or 6 desirable outcomes for the Murlocs.

Quite a bit of randomness

  • Bane of Doom – 21 Demons means a 4.8% chance of getting a certain one. Unlike other Active Reinforcement cards, the range of the swing is the biggest with this card, as cards costing from 1 to 9 can be summoned.
  • Blingtron 3000 – 23 weapons means a 4.3% chance of getting a certain weapon. Like Bane of Doom, there is a big range, from 1 to 7 cost weapons. Further, it goes both ways with weapons for both characters. Cards like Cursed Blade are a really bad outcome, while Doomhammer is pretty good.

High randomness

  • Mounted Raptor / Hungry Dragon – There’s a 2.1% chance for each particular 1-drop. While the 1-drops are typically slim pickings, cards like Injured Kvaldir and Flame Imp are pretty good gets.
  • Ran Wrangler – 48 beasts, means also a 2.1% probability for each beast. Also has a huge swing, with cards ranging from 1 to 9 cost. There are also 8 legendary beasts, so a not-bad 16% for one.

Very high randomness

  • Piloted Sky Golem – There’s a 1.2% for each 4-drop from the Sky Golem. Typically a solid 4-drop will have 4 or 5 attack and health. But sometimes, there are weak bodies like Twilight Drake and Dreadsteed, along with understated 4-drops with negated effects like Enhance-o-Mechano and Gnomish Inventor. Pit Lord or Piloted Shredder are probably the most desirable gets.
  • Piloted Shredder – This ubiquitous card has a 1.1% for each 2-drop. This makes the desperation “hit Shredder for Doomsayer” move a virtually 1 in 88. The best gets are Milhouse Manastorm, Wrathguard and Succubus.
  • Confessor Palestress / Sneed’s Old Shredder – There are somehow 92 legendaries in Hearthstone, meaning a 1.1% chance for each. Because legendaries are legendaries, these are typically good minions.
  • Effigy / RecombobulatorSummoning Stone – These cards scale reinforcement according to mana cost, giving the ability to virtually summon any minion. While most mana-costs are a lot of variability, the Effigy or Recombobulator of 8+ cost minons are exclusive to very powerful minions.
Hearthstone Screenshot 10-15-15 00.05.50
I am Mal’ganis, I am a turtle!
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The rare clone yourself reinforcement.


  • Active reinforcement usually is high-RNG. And the chances will get lower with more and more cards in the future.
  • Effects like Battlecry, Overload, etc don’t apply with the summoned cards, making normally unplayable minions with big stat points the best reinforcements.
  • No matter what is brought to the field as a reinforcement, typically, these are up-tempo cards, allowing “something” to be put on the board for presence. This gives these cards good value.


Elements of Hearthstone RNG: Jousts

Hearthstone’s The Grand Tournament (TGT) set brought about 2 new card mechanics. While Inspire has shown itself to be a viable and trusty mechanic, Jousting has turned the other cheek. While Jousting makes sense thematically, it is purely a mostly uncontrollable RNG factor. In the grand scheme of things, you are expected to win/lose half of your jousts to lose more jousts (since you lose ties), but it isn’t too far from 50/50 (high 40%s?). The only way to make sure you win most of your jousts are to fill your deck with North Sea Krakens and Giants.

  • Argent Lance – The Jousting weapon is a 2/2 for 2, which costs somewhere between 1.5 and 2 if you lose the joust, but is worth 3 for the 3 charges. A very small swing in either direction, especially how a 2 damage weapon isn’t that useful by turn 3-4.
  • Gadgetzan Jouster – By winning a joust, you get a 1-cost 2/3, which is a 1 mana swing, while losing the joust, you get a minion that’s a little less than 1. This isn’t a huge swing on paper, but getting a no-downside Zombie Chow on turn 1 is great for controlling the early game board.
  • Master Jouster – To my surprise, this card doesn’t have a huge swing on either side. By losing a joust, you get a 5/6 for 6, meaning you lose about 1 mana of tempo. With the divine shield and taunt, you get a minion worth a little over 7 or so, so you gain 1+ mana of tempo. Of course, it isn’t all in the numbers, as winning the joust could be a huge swing in a game decision.
  • King’s Elekk – Hey, a joust card that has no downside for losing! You just get a Bloodfen Raptor. But winning the joust will get you a draw of a free minion, which is a swing of about 2 mana in your favor.
  • Healing Wave – The only Joust spell costs 3, and can heal for 7 or 14. Healing for 7 is worth about 2.5 mana, while healing for 14 is worth about 5 mana.
  • Tuskarr Jouster – A 5/5 for 5 isn’t bad, given that it is only 1 life off from Pit Fighter. You can restore 7 life, or about 2.5 mana’s worth from winning a joust.
  • Armored Warhorse – You get a 5/3 for 4 mana, which isn’t a sexy stat line. By losing a joust, you’re getting 3.5 mana worth, but winning a joust is something better than 6 mana (Reckless Rocketeer).
  • The Skeleton Knight – A really bizarre card that has a deathrattle joust. You’re playing an overcosted Salty Dog (1 mana loss of tempo). If you actually win the joust, you’re getting a free Salty Dog! No wonder you never see this card.
Yeah I lost this joust real bad.
Yeah I lost this joust real bad.
All of the heals.
All of the heals.


  • Joust RNG is typically uncontrollable. Unless you stack a deck with big minions.
  • Swing on jousts typically are higher on the winner. The downside to losing a joust is a small loss in tempo typically.
  • The problem with jousts remain that you lose the “safe play.” By slotting in a joust card in a deck, you lose the guarantee of a sure thing, for more upside. This makes is a better arena mechanic than in ranked. Still not great in either format.

Elements of Hearthstone RNG: Passive Reinforcement

Moving along in the RNG series, I will get into what I call Passive Reinforcement, a card that gives you card that isn’t considering drawing from your deck. The new Discover mechanic in League of Explorers is a form of Passive Reinforcement, but I won’t get into those cards just yet. As opposed to Active Reinforcement, Passive Reinforcement adds a card to your hand.

Deck reinforcement

  • Captain’s Parrot/Sense Demons – Unlike the others in this class, these two cards solely help you draw a card that you have put into your deck. So really, there isn’t really much RNG for these cards. You can control it by putting useful pirates or demons in your deck, to ensure a good draw.

Limited options

  • Elite Tauren Chieftan – Good ol’ ETC has an awesome rock star intro but is nearly unplayable outside of a real casual game. You can get 1 of 3 cards, which cost 4 each, with the best card being a better Hammer of Wrath. The other 2 cards are typically not worth the 4 mana cost.
  • Ysera – On the other hand, Ysera gives you a chance to get 1 of 5 cards at the end of each turn, all being very good cards for their cost. They all work in different situations, but are all good in their own way.

Opponent dependency

  • Mind Vision – Mind Vision gives you a probability of copying a card in your opponent’s hand with 1/cards in hand. You can consider this card having more RNG against a control deck, and less so against a card that doesn’t draw a ton of cards. Obviously, this is a better against a deck that has good cards in it, rather than playing against a new player with a limited pool.
  • Thoughtsteal – Like Mind Vision, this card is better if your opponent has put good cards in their deck. Unlike Mind Vision, there is typically more RNG, as the deck is typically a bigger denominator to pick from than the hand. Also, it is likely that the higher-cost cards are picked, given mulligans typically aim to start off early game.


  • Neptulon – By the time League of Explorers comes out, there will be 14 collectible Murlocs. Neptulon adds 4 random murlocs to your hand, meaning that there will be a 7% chance to get each one.
  • Nefarian – Nefarian gives you 2 spell cards depending on the opponent. Roughly speaking, you will get a 3-5% chance to get a certain spell from a class. Certain classes (Mage, Shaman) will be better to steal against (Warrior, Paladin).

Playing the Lottery

  • Gazlowe – Gazlowe’s usage is dependent on how many 1-cost spells or spare parts you can find. However, once Gazlowe gets grinding, you can get 1 of 48 (2%) mechs added to your hand.
  • Webspinner – Right now Webspinner gives you a shot of 1 of 40 beasts (2.5%) upon death. Once the LOE adventure hits, it will be upped to 1 of 47 (2.1%).
  • Grand Crusader – This card adds one random Paladin card to your hand, which will be 1 of 48 Paladin cards by LOE (2.1%).
  • Burgle – You’re getting roughly a 2% chance at a specific class card. Unlike Nefarian, you can get minions or weapons as well. Class minions tend to be more usable than class spells, so it is a slightly more reliable card.
These knives are actually dipped in jormungar poison.
These knives are actually dipped in jormungar poison.
This is like the WoW Comic when Valeera got addicted to magics and Broll got mad.
This is like the WoW Comic when Valeera got addicted to magics and Broll got mad.


  • Passive Reinforcement typically involves giving up tempo to add random cards to your hand.
  • You can’t really control the randomness, unless you are using cards that depend on decks used.
  • Typically the swing of passive reinforcement RNG is low-risk, high upside. Getting a bad spell or a scrub minion is going to make you lose a game, as there is typically something to play on the board. But getting an amazing card through this method will give you a huge advantage.

Elements of Hearthstone RNG: Shaman/Range

Thrall lives and dies by the elements, but when he calls for a totem, it could be 1 of 4 characters. That in itself makes the Shaman the most random class in Hearthstone. The Shaman also specializes in cards that a provide a range, what I call “Shaman RNG.”

Did the 4 dead guys take 5 or 6 damage? We will never know.
Did the 4 dead guys take 5 or 6 damage? We will never know.


Lightning Storm/Elemental Destruction – The Shaman board clears go 2-3 damage or 4-5 damage, only proving a slim range in damages. To maximize the damage, try to get a Wrath of Air Totem out. Weaken bigger minions that don’t immediately dies from these spells. Play around these cards by having good-sized minions. You usually play around Lightning Storm (since it is more seen) by making sure all the minions on your board have more than 2 health. Having 3 health minions would put your minions at a 50% chance of dying. Having minions that are 4 or bigger will prevent any minions from dying off. Nobody really plays around Elemental Destruction, but maybe you can get a read off your opponent in the arena, as if they are going to play a Flamestrike.

Random Attack Points

Fireguard Destroyer – This card has a unique effect that no other has at the moment. For a cost of 5, you will get something between a 4/6 minion to a 7/6 minion. That makes a 25% chance of getting a 4/6, 5/6, 6/6, or 7/6. Basically, you have a 25% chance to get something that costs less than 5, a 25% chance to get something that costs exactly 5 (Pit Fighter), and a 50% chance to get something that is worth more than 5.

Single-Target Damage

Dr. Boom – As mentioned in the previous RNG post on pings, the Dr. has two types of RNG. Each Boom Bot hits a random character for 1-4 damage. The flying bombs will range from 2-8 damage combined. The most likely chance is 5 damage (33%), followed  by 4 and 6 (25%), 3 and 7 (12.5%) and 1 and 8 (6.25%). Ah, so that’s what those War Golem buff people are all meaning.

Imp-losion – This card hits one minion for 2-4 damage. Hitting for 2 will summon 2 1/1s, which is about 3 mana’s worth. Hitting for 3 will summon 3 1/1s, which is about 3.5 mana’s worth. Hitting for 4 will summon 4 1/1s, which is about 5 mana’s worth. There is a bit of swing here in terms of mana worth, with the 4 damage outcome being a great savings. It is boosted by spellpower, so that is a great combination to have for the arena, or some weird Malygos Warlock.

Crackle – With a 3 damage range affixed to a single-target spell, Crackle is the most RNG card of all these cards. 2 + 1 is basically a cost of 3. At 3 damage, you are only getting 2 mana’s worth. At 6, you are getting a Fireball, which is a spell that costs 4. When using Crackle, it’s best to hit a minion with health that gives you at least a 50% chance of killing it. Not a good idea to use it on a 6-health minion, since that gives you only the 25% chance for removal. Of course you can get screwed by 25% chance you get a weak shot. Again, this is boosted by the spellpower totem, which would ramp the damage to 3-7. Crackle’s RNG is more evident than that of other cards, since it can also go face.


  • The only way to take advantage Shaman RNG is to have spellpower. Dr. Boom and Fireguard Destroyer are at the whole mercy of randomness.
  • There isn’t much you can do here. Which puts Crackle in the group of one of the most frustrating cards ever, or one of the most miraculous ones.

Elements of Hearthstone RNG: Pings

I made a pact... to clear big taunts for lethal
I made a pact… to clear big taunts for lethal
The most common type of RNG in Hearthstone comes in the form of a card having an ability that will cause damage or destroy other characters, without actually attacking on it’s own. Unlike a Mage Fireblast, these “pings” go random places and cannot be targeted.
  • Battlecries and other one-time effects have less RNG than continuous effects or triggered effects, by virtue of the effect happening once.
  • Abilities that hit minions only have less RNG than those that can hit face.
One time effect, limited minions affected
Stampeding Kodo – The kodo is the least random card in the ping/attack class. It has a one-time effect to kill something that has 0, 1, or 2 attack. The effect is most effective (and has zero randomness) when there is only 1 opposing minion that has 0-2 attack on the board. It is clearly ineffective when the opponent has stacked 7 small creatures on the board (14% for each minion). Against 3+ attack minions, the kodo is just a bad tempo 3/5.
One time effect, one random minion
Bomb Lobber/Flamecannon – Bomb Lobber and Flamecannon have the same exact effect of dealing 4 damage to a random minion. Like the Kodo, it works best when there is one minion on the board with 4 or less health.
Deadly Shot/Sabotage – Same effect, except with a much bigger swing, as it completely destroys a minion. These random hard removals work best against one big thing on the board. The 4 cards above have probabilities to hit minions from 100% to 14%.
 Void Crusher – The Void Crusher is unique and doesn’t technically have a one-time effect. However, the potential to destroy itself upon inspiring really limits how long it will stay on the board. Also the amount of RNG is potentially doubled depending on how many minions are on each side. A board with 2 minions on each side will result in 4 possible outcomes, for a 25% chance. A board with 7 minions on each side will result in 49 possible outcomes, for a 2% chance. The chance of destroying a particular minion on each side remains at 14%.
One time effect, 2 minions hit
Forked Lightning/Multi-Shot/Dark Bargain – Like above, the fewer minions on the opposing side, the better the chances, however there is a minimum of 2 minions. Using these spells on a stacked board of 7 minions can result in 27 possible outcomes, for a small 3.7% chance. However, the chance of hitting a particular minion on a stacked side is about 28.5%.
One time effect, one character hit
Flame Juggler /Fist of Jaraxxus – The Flame Juggler is considered one of the better 2-drops in the arena, as it has the chance to snipe an annoying 1 health minion, like Worgen Infiltrator. Well, unless it hits the face. Any pings that open up heroes to attack are automatically more random than those that just target minions, as an extra target is provided. Though these pings are more dangerous (closer to lethal), their reliability of clearing a minion (what you typically want) is reduced by a big margin.
One time effect, 2 characters hit
Misdirection – Misdirection is unique, though it fits the one time effect being a secret, but causes 2 characters to run into each other. The RNG hurts the side with more minions, causing the possibility of 2 minions killing each other off. The only way this card has 0 RNG is if your opponent has 1 minion on the board while you don’t have any. This will cause a 100% probability of your opponent hero getting hit with their minion. Same goes will opponent hero attacking their own minion instead.
Two time effect, one character hit
Dr. Boom – Dr. Boom is unique in that he has Shaman RNG (damage range) and is the only card that will specifically allow for 2 independent instances of one character being hit. Each Boom Bot that is destroyed will have a chance to hit any one character on your opponent’s side.
Turn-based effect, one character hit
Ragnaros the Firelord – Pretty much the same probabilities as the above class, except the ping occurring each turn will help increase the number of instances occurring. The concept of flooding the board to prevent Rag from getting a lethal shot demonstrates the basic understanding of probability. Flood the board and he has a 12.5% chance to go face and end things.
Demolisher – These two cards have the same effect, except that the Demolisher has slightly more RNG than Ragnaros. Because Ragnaros will hit after your turn, it means you can actively help reduce the number of minions on the board, in order to increase the probability of something getting hit. Demolisher hits at the start of your turn, which means, your opponent has a chance to set up a board to reduce the probability of something getting hit.
One time effect, multiple missiles
Arcane Missiles/Goblin Blastmage/Avenging Wrath – With more pings comes more RNG. The health of opposing minions matters more than ever with these. If a board with all 1-health minions is hit by Avenging Wrath, each dead minion will increase  the probability of the other minions are getting hit. A minion that is hit and dead will not get overkilled, and thus increase the probability of another getting hit. Another example, let’s say it’s turn 4, you have a Target Dummy and your opponent summons an Evil Heckler (5/4). You drop Blastmage. Because each ping has a 50% chance to hit the Heckler, the chance of the Blastmage killing the Heckler is a little over 6%. Let’s say same scenario, but instead of an Evil Heckler, your opponent plays Mini-Mage (4/1). The Blastmage still has 50% chance of hitting the minion, but there is an almost 94% chance the Mini-Mage will get killed.
Triggered effect, one character hit
Ship’s Cannon/Eydis Darkbane – Triggered ping minions are interesting because they can provide a good deal of RNG or none at all. Their effects are typically more useful in decks built around them, meaning they can do more damage in constructed. Ship’s Cannon and Eydis Darkbane can be picked in the arena, and due to the lack of synergy or an incompatible class, never have their effects activated at all. The Knife Juggler will always have it’s effect activated (as you’ll always have minions), while the Shadowboxer will always have it’s effect activated (so long as a Priest can spend mana to heal.) These cards have a little more RNG than the one-time effect minions, as there are more chances for their effects to hit. Ship’s Cannon and Eydis Darkbane cannot throw multiple shots in one turn, and instead have an independent event for each trigger.
Knife Juggler/Shadowboxer – While these 2 minions have the weaker ping effects, they are hybrids of one character hit and multiple missiles types. Knife Juggler will throw multiple knives in one instance if 2 minions are summoned at once, or if a card like Unleash the Hounds is played. Shadowboxer will throw multiple punches in one instance if Holy Nova is used, and multiple characters are healed. As described above, the health of opposing minions matters more in affecting the randomness for multiple missile cards.
Triggered effect, multiple missiles
Flamewaker – The Flamewaker is unique on the RNG list in that it is the only true trigger multiple ping. Cast a spell, and 2 pings will be sent at opposing characters. While the RNG of each trigger is lower than a Goblin Blastmage, the ability to cast multiple instances of pings will help increase the RNG.
Turn-based effect, one minion hit, either side, most minions effected
Fel Cannon – Fel Cannon finally brings about the concept of friendly fire. This essentially doubles the amount of RNG, as the amount of minions is potentially doubled. On a board state with 7 minions on either side, Fel Cannon has a 7.7% chance to ping any particular minion. Because Fel Cannon can’t hit itself, the probability of your minion getting hit (46%) is lower than that of your opponent’s getting hit (54%). The rub is that Fel Cannon will not hit any mechs, so if your opponent plays mechs, the Fel Cannon can backstab your own board.
Warrior RNG
Brawl – Oh hey, the Warrior is a roulette player sometimes. Brawl RNG is pretty simple, as the side that has more minions is more likely to have a minion live. Any opposing boards with the same number of minions on each side will be a 50% coin flip for who wins the brawl. Brawl is funny, as The Warrior typically doesn’t care if he wins the Brawl. Brawl is typically played as a board clear (who cares who dies, as long as there is one minion left) or to kill one big threat.
Bouncing Blade – The same concept with Brawl, except the cumulative health points of minions will help determine the probability here. A side with 2 Yetis (4/5) has a 67% chance to win a Bouncing Blade foray over a side with 1 Yeti. While cumulative health totals are important here, the appearance of a low-health minion is even more important, as Bouncing Blade ends once a minion dies. So, the side with a one health minion is a the greatest disadvantage of that minion dying. There is no real way to calculate the probability of this card, as every situation is different. Much situational RNG.
One-time effect, multiple missiles, any character hit
Mad Bomber/Madder Bomber – These goblins are used in promotional work for Hearthstone and happen to be the most RNG cards in the game. Sticks of dynamite are thrown haphazardly 3 or 6 times, at any character on the board. While they are typically used to clear a board, enraging your own minions can serve some utility as well. Let’s go through a specific case, ADWCTA’s Gahz’rilla Dream.
I do not own this. It was stolen off ADWCTA's YouTube. Source: https://www.youtube.com/watch?v=5tgyOg795Dg
I do not own this. It was stolen off ADWCTA’s YouTube. Source: https://www.youtube.com/watch?v=5tgyOg795Dg

The premise here is that Gahz’rilla needed to be hit by 2 out of 6 Madder Bomber pings to grow to 24 attack and win the game. There are 8 characters on the board (Uther, Mad Bomber, 2 Silver Hands, Faerie Dragon, Youthful Brewmaster, Gazh’rilla, Rexxar).

Bomb 1 – Rexxar
Bomb 2 – Gahz’rilla
Bomb 3 – Mad Bomber
Bomb 4 – Faerie Dragon
Bomb 5 – Rexxar
Bomb 6 – Gahz’rilla
Gahz’rilla got hit 2 times. What were the chances of that happening?

(Disclaimer: This math could be very wrong)

8 characters, 6 flips of dynamite

8^6 = 262144 possible independent events

2 Gahz = GahzA, GahzB

_ _ _ _ _ _

GahzA = 6 spots; GahzB = 5 spots

_ _

Gahz A = 2 spots; GahzB = 1 spot

# of possible outcomes = (6 x 5) / (2 x 1) = 15 possible outcomes where Gahz is hit exactly 2 times

Probability = 15 / 262144 = 0.0000572%

The math is not completely correct, as if one of the opponent minions died, the chances of hitting Gahz increase for each minion death.

As seen the bombers make for extreme RNG, as there are so many different combinations/permutations to consider. But they also make for some great moments now and then.

  • This is the most common form of RNG in Hearthstone as of now.
  • Ping RNG is typically countered by playing more minions on the board to reduce the chances of particular minions getting hit.
  • Conversely, to make the RNG work in your favor, reduce the number of minions on the board to have a better chance of hitting the desired target.
  • Health of minions matters more for some types of this RNG.
  • Minions with trigger pings or turn-based pings allow for more events to occur.
  • Don’t try to do the math for Madder Bomber probability. It literally took me a whole day, and I’m not sure I got it right.

The Elements of RNG: An Introduction

If you’ve ever browsed a forum, blog, or website about gaming, there’s a good chance you have encountered the phrase “RNG.” The acronym itself stands for “random number generator” and typically refers to any random element in a game, or anything subject to probability/chance. As it stands, RNG remains a major issue for Hearthstone.

Typically, RNG is invoked as a complaint by more experienced players losing a game to lesser experienced players, and it does provide a fudge factor in reducing the gap between skill levels. The level of RNG in Hearthstone has often been used by blowhards as the prime reason why they have quit the game. At other times, the RNG in Hearthstone is said to be a good thing, or something that made the game unique. Often, an instance of extreme RNG serves as an amazing highlight reel shot.

So how much RNG is there in Hearthstone? I sought to find out.

What this is

  • I pored over every collectible card in Hearthstone released so far. I was able to bin every card containing a random element into a type of RNG. I was able to discern 14 types of RNG.
  • Some cards have so much randomness, they fall into multiple bins!
  • I try to rank the amount of randomness of each card in each bin.
  • I try to talk about how people lessen the randomness and increase their odds of success.

What this is not

  • I don’t compare Hearthstone RNG to that of other games.
  • I’m not taking a side about whether RNG is bad or good for Hearthstone. I am objectively talking about each type of RNG.

Truth about card games

  • Here’s the inconvenient truth. Every card game has RNG. As long as cards are drawn from a deck, there is an element of probability of what card you get.
  • There is a 30 card requirement in a Hearthstone deck. That means there is a 3.33% of drawing a single card. In constructed, the randomness of drawing cards is reduced by including 2 copies of a card. This means there is a 6.67% chance of drawing it.
  • Cards like Varian Wrynn and Far Sight and Call Pet aren’t really RNG. Cards that have randomness depending on card draw are just at the mercy of being in a card game.
  • The same goes for topdecking. Sure it’s luck you drew the card you needed for lethal, but it’s just the nature of randomness in a card game.

The remaining posts of the RNG series will discuss in depth each of the 14 bins I identified as a source of RNG in Hearthstone.

Stay tuned!