'Ello. Any open spaces here or are you too far along?
The sunken world (Passive): Wherever she steps the world under her feet changes into a portal to a decrypted ancient place that mirrors the above the world completely sunken underwater and nearly devoid of life. Unless Evelune is grabbing ahold of someone she is the only person who can enter that portal, this allows her to turn any surface into a swimmable one, the area she is directly under will also change into a portal that moves with her as she swims through the sunken version of the real world, though her speed in the water is nearly four times as fast as when she's on land. Additionally it should be noted that the portal that leads to the Sunken World can be expanded to a massive twenty foot radius around her body.
Devil Arm:
At first it was a long scimitar forged of fine metals that held the force of a hundred tidal waves within each blow
Test of soul / Undertoe: Eve can drag people under to the sunken world from the surface world if she has at least part of her body already submerged, only the person pulled and Eve herself can exit at this point and if the target can manage to fight their way to the surface they will be inflicted with a curse that will open a portal under their feet that which they themselves cannot enter but reveals their position to Eve for five minutes.