Knull, Lord of the Abyss

+2: Create two 2/2 Black Symbiote Creatures with Deathtouch, Lifelink and indestructible.
-4: Symbiote creature you control gain +3/+3, Creatures your opponent controls lose -3/-3.
-X: Destroy creatures your opponent controls with converted mana cost of X, creatures killed this way return as 2/2 Symbiotes under your control.