Riot

Target 1 face-down Defense Position monster on the field; return it to the hand, then the player who added it to their hand can Special Summon 1 monster from their hand in face-down Defense Position. When an opponent's monster declares an attack: You can banish this card from your GY; change 1 face-down Defense Position monster on the field to Attack Position. You can only use each effect of "Riot" once per turn.