Once per turn, during your Main Phase, if you control this monster on the field, you can equip it to a face-up monster on your side of the field as an Equip Card, OR unequip the Union equipment and Special Summon this card in face-up Attack Position. While equipped to a monster by this card's effect, that monster will be unaffected by the effects of Spell Cards controlled by your opponent. (1 monster can only be equipped with 1 Union Monster at a time. If the monster that this card is equipped to is destroyed as a result of battle, destroy this card instead.)