Number F0: Utopic Future Slash (Secret Rare) [BLAR-EN046-SeR]

2 Xyz Monsters with the same Rank, except "Number" monsters
(This card's original Rank is always treated as 1.)
You can also Xyz Summon this card by using a "Utopia" monster or "Number F0: Utopic Future" you control as material. (Transfer its materials to this card.) Gains 500 ATK for each "Number" Xyz Monster in the GYs. Cannot be destroyed by battle. Once per turn: You can detach 1 material from this card; this card can make a second attack during each Battle Phase this turn.