If this card is in your hand or GY: You can Tribute 2 WATER monsters; Special Summon this card. You can only use this effect of "Citadel Whale" once per turn. If this card is Special Summoned: You can Set 1 "Sea Stealth Attack" directly from your Deck. Once per turn, when your opponent activates a card or effect that targets 1 WATER monster you control (and no other cards) (Quick Effect): You can negate the activation, and if you do, destroy that card.
In order to have 2 WATER Tributes on the Field, you will need to fill your Field fast, and these monsters are able to do so. Hammer Shark can Special Summon another level 3 WATER monster from your hand during the same turn, Lekunga can banish 2 WATER monsters from your Graveyard to Special Summon 1 “Lekunga Token”. You can also use Big Wave Small Wave to destroy at least 1 WATER monster on your Field to Special Summon Citadel Whale.
similar ignition effect to red eyes slash same amount of cards (if special summoning to your hand) but has the ability to set a powerful card as opposed to special summoning a warrior type monster when its destroyed. interesting to see if it will become higher than a teir 4 deck with combos between hammer shark, the new spell that lets you raise levels of your water type monsters while being treated as umi face up and the skill beatdown