Lore3 or more Level 7 monsters
You can also Xyz Summon this card by using 1 "Number C20X", "Xyz Dragon", or "Odd-Eyes" Xyz Monster you control as the Xyz Material. (Xyz Materials attach to that monster also become Xyz Materials on this card.) This card gains 1000 ATK for each Xyz Material attach to it. You can target 1 "Number", or Dragon-Type Xyz Monster in your Graveyard, or face-up in your Extra Deck; until your opponent's next End Phase, this card's name becomes that monster's, and replace this effect with that monster's original effects. You can only used the effect of "CXyz Doomsday Zarc Dragon" once per turn.