Target 1 face-up monster your opponent controls that was Special Summoned from the Extra Deck; change its ATK to 0, and if you do, negate its effects. If your opponent Special Summons a monster(s) from the Extra Deck while this card is in your GY, except the turn this card was sent to the GY: You can Set this card. You can only use each effect of Titanocider once per turn.