The effect of “Maiden of the Aqua” is active only when there is no face-up Field Spell Card on the field. When a Field Spell Card is activated after “Maiden of the Aqua” is Summoned, the effect of “Maiden of the Aqua” is negated as long as there is a face-up Field Spell Card. If the only Field Spell Card is face-down, the effect of “Maiden of the Aqua” is active. If there is a face-up Field Spell Card but it is negated by “Imperial Order”, the effect of “Maiden of the Aqua” is not active.
If a Field Spell Card is already active, and “Maiden of the Aqua” is Summoned, the existing Field Spell Card continues to function and “Maiden of the Aqua”’s effect is not applied until there is no face-up Field Spell Card.
While “Maiden of the Aqua” is making the field “Umi”, you can activate “Tornado Wall” but if “Maiden of the Aqua” is destroyed, “Tornado Wall” is also destroyed.
If “Maiden of the Aqua”, “Umi”, and “Tornado Wall” are all on your side of the field, and “Umi” is destroyed, “Tornado Wall” is not destroyed because “Maiden of the Aqua” treats the field as “Umi” as soon as “Umi” leaves play.
If you have “Maiden of the Aqua” (with her effect active) and “The Legendary Fisherman” or “Deepsea Warrior” on your side of the field, and “Dark Hole” is activated, “The Legendary Fisherman” and “Deepsea Warrior” will not be destroyed.
If you have “Maiden of the Aqua” and “Tornado Wall” on the field, and “Maiden of the Aqua” is attacked by “Dark Driceratops” and Battle Damage would be inflicted, “Tornado Wall” still prevents the damage during damage calculation, as “Maiden of the Aqua” will remain on the field until the end of the Damage Step.
Netrep Rulings:
“Maiden of the Aqua” is not a valid Tribute for “Levia Dragon - Daedalus’s” effect.