Poseidra Burst, the Atlantean Dragon Overlord
3 Level 7 WATER Sea Serpent-Type monsters
You can also Xyz Summon this card by using 2 Rank 4 or higher WATER Xyz Monsters you control as the Xyz Materials. (Xyz Materials attached to those monsters also become Xyz Materials on this card.) If you do, its effect cannot be activated this turn. Once per turn: You can detach 2 Xyz Materials from this card; destroy all face-up cards or all Set cards your opponent controls. Face-up WATER monsters in your possession gain 300 ATK and DEF for each card destroyed by this effect until the End Phase.