If your opponent controls a monster(s) Special Summoned from the Extra Deck and you do not: Choose 4 "Number" Xyz Monsters from your Extra Deck with different Ranks, plus a 5th "Number" Xyz Monster whose "Number" value in its name equals the combined "Number" values of the 4 other monsters, Special Summon that 5th "Number" monster (this is treated as an Xyz Summon), and attach the 4 chosen monsters to it as material, but you cannot Special Summon monsters, except "Number" Xyz Monsters, while you control that face-up monster.