You can reveal 1 "Number" Xyz Monster in your Extra Deck; Special Summon this card from your hand. If you do, this card's Level becomes the revealed monster's Rank, also while it is face-up in the Monster Zone, you cannot Special Summon monsters from the Extra Deck, except "Number" Xyz Monsters. You can only use this effect of "Astral Kuriboh" once per turn. A "Number" Xyz Monster that was Summoned using this card on the field as material gains this effect. Cannot be destroyed by battle or your opponent's card effects.