Vicious Shadows

Oracle Text

Whenever a creature dies, you may have Vicious Shadows deal damage to target player equal to the number of cards in that player's hand.

Card Rulings

10/1/2008 The player you target doesn’t have to be the controller of the creature that was put into a graveyard.
10/1/2008 The number of cards in the targeted opponent’s hand is checked only when the ability resolves.