During the Main Phase, you can: Immediately after this effect resolves, Xyz Summon 1 Xyz Monster, using only "Goblin" monsters you control. If you control a "Goblin" Xyz Monster: You can target 1 Effect Monster on the field; detach 1 Xyz Material from a monster on either field, and if you do, negate that monster's effects until the end of this turn. You can only use 1 "Goblin Biker Grand Stampede" effect per turn, and only once that turn.