Ninja Strike 7 (Whenever your opponent attacks or blocks, if you have 7 or more cards in your mana zone and you haven't used a Ninja Strike ability this attack, you may summon this Shinobi without cost. At the end of the turn you used this ability put this Shinobi on the bottom of your deck.) When you put this creature into the battle zone, choose 1 of your opponent's creatures. During this turn, that creature gets -6000 power. When this creature is destroyed and you have at least 1 darkness card in your mana zone, you may put 1 of your shields into your graveyard instead.