Z-Metal Tank

Once per turn, during your Main Phase, if you control this card on the field, you can equip it to your X-Head Cannon or Y-Dragon Head 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, increase the ATK/DEF of the equipped monster by 600 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.).