Mogh, Lord of Blood

Flying, lifelink

Creature spells have bloodthirst.

Pay 5 life: Proliferate.

Whenever a creature deals combat damage to a player, if it had 5 of more +1/+1 counters on it, that player loses a third of his life rounded down. If that creature had 10 or more +1/+1 counters on it, that player loses half his life rounded down instead. If that creature had 15 or more +1/+1 counters, that player loses the game instead.