Poseidra, the Rumbling Atlantean

Your opponent's monsters cannot target this card for attacks while you control a monster other than "Poseidra, the Rumbling Atlantean". You can only use each of the following effects of "Poseidra, the Rumbling Atlantean" once per turn. You can send 1 other WATER monster from your hand or face-up field to the GY; Special Summon this card from your hand. If this card is Normal or Special Summoned: You can send 1 "Atlantean" or "Mermail" monster from your Deck to the GY, then target 1 card your opponent controls; return it to the hand.