Yogg-Saron – Making Sense of Insanity

Yogg-Saron was released today, and he (it?) promptly became the manifestation of RNG itself.


This effect prompted a flurry of questions on Twitter, clarifications of Yogg-Saron can be found in this well-arranged thread.

Like the Master of Evolution, I wanted to know what the raw probabilities of things happening were. How insane will this Old God be?


  • All 224 collectable spells so far from Basic, Classic, GvG, Naxx, BRM, TGT and LoE. Old Gods is not included, and neither is the distinction between Wild and Standard Play. A future update might have these figures.
  • I calculated percentages for “Target affected.” These will add up to 100%.
  • I calculated percentages for Spell Type. These do not add up to 100%, as some spells have multiple abilities in one card.
  • Choose one cards are a 50% probability, so are counted as half cards for each effect.
  • Certain cards have a less than 100% probability of the effect carrying out. Such cards include 4 Demon spells and certain cards that draw for you when something dies. I chose not to deduct probability from these cards, but just know the percentages are slightly inflated. So these are assumptions that I made for this data.

Target affected

Yogg effect

  • All characters (both teams) – no target, everyone is healed or damaged
  • All minions (both boards) – no target, every minion is affected
  • One board – 50% probability of something happening to the top or bottom of the board. Could be AOE, reinforcements, etc.
  • One character – probability divided among all characters (minions + 2 heroes)
  • One hero – 50% probability of either hero getting benefit or harm
  • One minion – probability divided among all minions on the board
  • One team (minions + hero) – 50% probability of either team
  • Secrets – kept separate, as they interact with various characters at different junctures

Spell type

Yogg type.PNG


  • Buff – exclusive to minions, anything that helps a minion in someway. This figure is overinflated, in should be closer to 14%, not including the demon buffs.
  • Damage – any time some character loses health
  • Debuff – a negative effect that isn’t damage, like health reduction, silence, or freeze
  • Hard Removal – exclusive to minions, a minion is destroyed without damage being dealt
  • Heal – any time some character gains health
  • Reinforcement – any time a minion is summoned to the board by card effect
  • Resource Gain – exclusive to heroes, any gain in mana crystals, card draw, deck additions
  • Secret – secrets kept separate
  • Weapon – exclusive to heroes, any time a hero is granted attack

A few spells didn’t really fit into the traditional bins.

  • Shadowform – I put it under the “Weapon” bin, as it allows a steady damage source to enemy minions or faces
  • Astral Communion – I begrudgingly put this under “Resource Gain.” It affects resources, but will have an actual negative effect, as Yogg can’t be played before Turn 10.
  • Beneath the Grounds – This is a delayed reinforcement, so I put it under “Reinforcement.”
  • Confuse – I put this as 1/2 Buff and 1/2 Debuff. It is too complicated to know whether there is any benefit when Confuse is played, so I split the difference.

What this tells us

  • 30% of the Yogg-Saron’s spells affect only 1 minion at a time.
  • Pyroblasts to the face are always a concern, but only 36.4% of spells will affect the heroes. This makes Pyroblasts to the face less likely than perceived..
  • Hard removal to a minion will occur 13% of the time.
  • 1 of 10 of Yogg-Saron’s spells will be secrets.
  • Most spells are some kind of damage (35%), with some resource gain occurring in about 1/5 of spells.
  • Overall, Yogg-Saron seems more fun than good, as his battlecry will cause the game to be a virtual coin flip. Of course the hero with higher health and minions on the board will have a better chance of withstanding whatever comes from the battlecry.

4 thoughts on “Yogg-Saron – Making Sense of Insanity

    1. It’s safe to say that every time Yogg-Saron is played, there will be a unique outcome in terms of spells and sequence. The math in calculating one outcome will be crazy in it’s own, with some number requiring negative exponents.

      Liked by 1 person

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