Once per turn, during your Main Phase, if you control this card on the field, you can equip it to your "X-Head Cannon" as an Equip Spell Card, OR unequipthe Union equipment and Special Summon this card in face-up Attack Position. While equipped to a monster by this card's effect, increase the ATK/DEF of the equipped monster by 400 points. (1 monster can only be equipped with 1 Union Monster at a time. If the equipped monster is destroyed as a result of battle, destroy this card instead.)