2 Level 4 monsters with the same Attribute
You can detach 2 Xyz Materials from this card; Special Summon from your Extra Deck, 1 Rank 7 or lower "Arc Des" Xyz Monster, except "Arc Des Judgment Dragoon", and if you do, attach 2 "Arc Des" Trap Cards from your hand and/or field to that monster as Xyz Materials. (This Special Summon is treated as an Xyz Summon.) During your opponent's Main Phase or Battle Phase, you can: Immediately after this effect resolves, Xyz Summon 1 "Apocalyptic Knight - Arc Des Judgment Wyvern" or "Apocalyptic Knight - Arc Des Frost Wyvern" from your Extra Deck, using this card and 1 WATER "Arc Des" Xyz Monster you control as the Xyz Materials. You can only use 1 "Arc Des Judgment Dragoon" effect per turn, and only once that turn.