Mordigal, the Writhing Mass

Mordigal, the Writhing Mass has all the abilities of creatures exiled with it, and gets +X/+X, where X is the total power of the creatures exiled with it.
When Mordigal, the Writhing Mass leaves the battlefield, return all creatures exiled with it to their owner's graveyard.
{3}: Exile a creature from your graveyard.