Slithermuse
From Lorwyn Eclipsed Commander set
Slithermuse
Creature — Elemental
3/3
When this creature leaves the battlefield, choose an opponent. If that player has more cards in hand than you, draw cards equal to the difference.
Evoke (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)
Rulings
- You choose an opponent when the ability resolves. Once you determine how many more cards than you that player has, that number is locked in as the amount you'll draw.