Xyz Slidolphin

If an Xyz Monster(s) is Special Summoned to your field (except during the Damage Step): You can Special Summon this card from your hand. If an Xyz Monster(s) is Special Summoned to your field while this card is in your GY, except the turn this card was sent to the GY (except during the Damage Step): You can target 1 of those monsters; attach this card to it as material. You can only use each effect of "Xyz Slidolphin" once per turn.