Asheara, the Abysswalker

When Asheara, the Abysswalker enters the battlefield, any number of target creatures from your graveyard and put an abyss counters on them.
Remove abyss counter from a creature in your exile:
-You gain X life, where X is the creature power, rounded down.
-You draw X cards, where X is the creature toughness, then you lose that many life.
-Put target creature card from your exile onto the battlefield under your control. You lose life equal to its converted mana cost.