Thuurax, Apex of Slaughter

Mutate {4}{u/r}{b}{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.)
Whenever this creature mutates, each opponent sacrifices a creature and you choose a creature
card in your graveyard. Return those creatures to
the battlefield under your control. They gain
Haste and can't be blocked this turn.