Bomb

At the beginning of combat on your turn, put a
+1/+1 counter on Bomb.
Whenever Bomb blocks or becomes blocked by
a creature, Sacrifice Bomb. Bomb deals damage
equal to it's power or toughness to that creature.
If Bomb's power or toughness are greater than or
equal to 5, Sacrifice Bomb. Bomb deals 5 damage
to target creature or player.