Poseidra Abyss, the Atlantean Dragon Lord (Quarter Century Secret Rare) (ROTA-EN043)

3 Level 7 monsters
Once per turn, you can also Xyz Summon "Poseidra Abyss, the Atlantean Dragon Lord" by using 1 "Atlantean" or "Mermail" Xyz Monster you control. (Transfer its materials to this card.) Once per turn: You can detach 2 materials from this card, then send 1 WATER monster from your hand or Deck to the GY; return up to 3 cards your opponent controls to the hand. If this Xyz Summoned card is sent to the GY: You can discard 1 card to the GY; Special Summon 3 Level 3 or lower Fish, Sea Serpent, and/or Aqua monsters from your hand and/or GY.