Ilde kicks her sandals off as she flings herself into the water after him - she doesn't think, only reacts, the illusion disappearing even if her clothes mean it isn't replaced by a tail. It doesn't matter; she's a creature of the river with or without it, and her legs will drive her as far under as she needs to be to slide her hands under Wolfgang's arms before he can disappear entirely. Her physical strength is neglible and no match for that of the indistinct form grasping the other end of him, a blur of rage and the female form, but it isn't physical strength she relies on when she spreads her influence through the water and wills it to obey her, wrestling with the spirit for dominance in what should be her domain first. It's an undignified fight, Ilde pushing and struggling with the woman's grip with her feet as she tries to pull and push Wolfgang higher toward the surface--

--later she'll wonder what good she thinks it's going to do to kick a ghost in the face, but the water is behind her and she pulls hard.