Time Rewinder

If a monster(s) on the field is flipped face-up during the Main Phase: You can Special Summon this card from your hand, then change 1 face-up monster on the field to face-down Defense Position. If this card is flipped face-up during the Main Phase: You can target 1 monster in your GY; Special Summon it in Defense Position, then change 1 face-up monster on the field to face-down Defense Position. You can only use each effect of "Time Rewinder" once per turn.