Carnage, Venom Spawn

Mutate {3}{b}{r} (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.)
Bloodthirst 2 (If an opponent was dealt damage this
turn, this permanent enters the battlefield with two
+1/+1 counters on it.)
Frenzy 1 (Whenever this creature attacks and isn't blocked, it gets +1/+0 until end of turn.)