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Shifter Zerus Detalailed Explanation
Most things that happen in battlegrounds take from a shared pool of minions that everyone has access to. When the pool has less minions in it then it is harder to find.
For example Tavern tier 6 minions have only 6 copies each in the shared pool.
Shifter Zerus is the exception to this. When you play him from your hand you are effectively adding 1 more minion to the pool. So if you played him as Mama Bear there would now be 7 copies of Mama bear total available. (after you die that Mama Bear goes back to the shared pool of 7).
Shifter Zerus has an equal chance of transforming into any minion, without regard to the current pool or tavern tier of that minion.
I answered this question wrong once in the past so wanted to clarify.
edit: oops spelled the title wrong, :)
Mike Donais
Discover uses the pool to determine what it shows you.
Discover pulls from the pool.
Only shifter adds to the pool and breaks the pool rules.
Mike Donais
It random.
Mike Donais
Yes