Brigan, Apex of the Torch

Mutate {r/w}{b} (If you cast this spell for its mutate
cost, put it over or under target non-Human creature
you own. They mutate into the creature on top plus
all abilities from under it.)
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Whenever this creature mutates, it deals
damage to each player equal to its power.
Then, if you have 10 or less life, it gains
haste and lifelink until end of turn.