Oath of Ghouls

Enchantment, 1B (2)
At the beginning of each player's upkeep, that player chooses target player whose graveyard has fewer creature cards in it than his or her graveyard does and is his or her opponent. The first player may return a creature card from his or her graveyard to his or her hand.¹
Illus. Brom

Gatherer Card Rulings [Nov 2009]

• 10/1/2009: The ability can only target an opponent of the current player.
• 10/1/2009: The targeted player's graveyard having fewer creature cards in it than the current player's is a part of the targeting requirement. A player can't be targeted by this ability unless it's true, and the ability will be countered on resolution if it's no longer true at that time.

Format Legality	Legal in Vintage, Legacy Banned in Extended, Standard, MTGO Classic
Printings (1/6)	Exodus (Rare)