Sardag, Seed of Mutation

This creature has Ward {2} for each time it's been
cast from the command zone this game.
Whenever this creature mutate, put a +1/+1
counter on it and draw a card.
Whenever an opponent's creature would dies,
instead exile it under this creature.
Ferocious—{x}{w/b}: You may mutate a creature of
mana value X exiled under this creature as tough
it had mutate on this creature.