During your next turn, you can Special Summon this card and use it and "Gantala" to Xyz Summon a Rank 7 Xyz Monster.
Banish this card from the Deck with "Gold Sarcophagus" and you can immediately replace it with other WATER Dragon-Type monster.
This card works great in setting up Rank 7 plays in "Mermail" decks. Because Mermails fill up the Graveyard with ease, you can fulfill this card's summoning conditions with little effort and without banishing cards from your hand, and because it is Level 7, it is compatible with Level 7 Mermails such as "Mermail Abyssmegalo" for Xyz Summoning.
"Nimble Sunfish" can set up the grave with fodder for continued use of this card.
By discarding "Stream, Dragon Ruler of Droplets" and another WATER monster, you can Special Summon one copy of this card from the deck, and if you have another one in your hand, banish "Stream" and the other WATER monster to Special Summon it and have access to a quick Xyz Summon, with almost no hand advantage loss.