Card Rulings:Levia-Dragon - Daedalus

You can send "A Legendary Ocean" to the Graveyard to activate "Levia-Dragon Daedalus"' effect, but you can't send "Maiden of the Aqua".

You can't send a face-down "Umi" or "A Legendary Ocean" to activate "Levia-Dragon Daedalus"' effect.

If you activate "Levia-Dragon Daedalus"' effect and your opponent chains "Ring of Destruction" to destroy "Levia-Dragon Daedalus", "Levia-Dragon Daedalus"' effect still resolves even though it has been destroyed.

When "Book of Moon" is chained to "Levia-Dragon Daedalus"' effect to flip it face-down, the effect still resolves, but "Levia-Dragon Daedalus" is destroyed by its own effect, since it's no longer "this card", it's just "a card".