Grizzleback

Possession {x} (You may pay {x} as an additional cost when you play this card. This creature gets +X/+X for each mana spent)
If at least {b}{b}{b} was spent to cast this card, Grizzleback gains trample.
If at least {b}{b}{b}{b}{b} was spent to cast this card, Grizzleback gains deathtouch and lifelink.