Y-Dragon Head (KC01-EN028) - 25th Anniversary Ultimate Kaiba Set Unlimited

Once per turn, you can either: Target 1 "X-Head Cannon" you control; equip this card to that target, OR: Unequip this card and Special Summon it. A monster equipped with this card gains 400 ATK/DEF, also if the equipped monster would be destroyed by battle or card effect, destroy this card instead.