Poseidra, the Atlantean Dragon – (Realm of the Sea Emperor Structure) – (SDRE-EN001) – (Ultra Rare)(ITL)

You can Tribute 3 Level 3 or lower WATER monsters; Special Summon this card from your hand or Graveyard. When you do: Return all Spell and Trap Cards on the field to the hand, and if you do, if 3 or more cards are returned to the hand by this effect, all monsters your opponent currently controls lose 300 ATK for each.