Oath of Druids

Enchantment, 1G (2)
At the beginning of each player's upkeep, that player chooses target player who controls more creatures than he or she does and is his or her opponent. The first player may reveal cards from his or her library until he or she reveals a creature card. If he or she does, that player puts that card onto the battlefield and puts all other cards revealed this way into his or her graveyard.¹
Illus. Daren Bader

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 controlling more creatures than the current player 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 Banned in Legacy, Extended, Standard
Printings (2/7)	Judge Gift Program (Special) Exodus (Rare)