Jace's Phantasm | Magic: The Gathering
Formats Jace's Phantasm is Legal in
Official Oracle Text for Jace's Phantasm
Jace's Phantasm gets +4/+4 as long as an opponent has ten or more cards in his or her graveyard.
Official Rulings for Jace's Phantasm
7/1/2012 : In a multiplayer game, a single opponent must have ten or more cards in his or her graveyard for the bonus to apply, although this opponent may change over the course of the game. You don't have to pick a single opponent; the ability will monitor each opponent's graveyard.