Vylon Pentachloro (HA06-EN037) - Hidden Arsenal 6: Omega Xyz Unlimited

Once per turn, you can either: Target 1 face-up "Vylon" monster you control; equip this card to that target, OR: Unequip this card and Special Summon it in face-up Attack Position. While equipped by this effect, if the equipped monster destroys an opponent's monster by battle: You can target 1 card your opponent controls; destroy that target. (A monster can only be equipped with 1 Union Monster at a time. If the equipped monster would be destroyed, destroy this card instead.)