Harbinger, The First

Flying, Deathtouch, Annihilator 5

{x},{t}: Untap target creature you control with converted mana cost {x}, it gets Haste and
+2/+2. Then sacrifice that creature at the beginning of the next end step.

Whenever you sacrifice a creature, you gain 1
life.Whenever an opponent sacrifices a creature, they lose 1 life.