Whenever a creature you control attacks or a creature you control enters attacking, you may pay . If you do, you may put a creature card with mana value less than that creature's mana value from your hand onto the battlefield tapped and attacking.
Arni Metalbrow (Halo Foil) (MAT-200) - March of the Machine: The Aftermath: (Showcase) Foil
Whenever a creature you control attacks or a creature you control enters attacking, you may pay . If you do, you may put a creature card with mana value less than that creature's mana value from your hand onto the battlefield tapped and attacking.
