You can send 1 "Atlantean" monster from your Deck to the GY, except "Neptabyss, the Atlantean Prince"; add 1 "Atlantean" card from your Deck to your hand, except "Neptabyss, the Atlantean Prince". If this card is sent to the GY to activate a WATER monster's effect: Target 1 "Atlantean" monster in your GY, except "Neptabyss, the Atlantean Prince"; Special Summon it. You can only use each effect of "Neptabyss, the Atlantean Prince" once per turn.