I don't think having a vore only challenge that "cucks" the wand damage is a good idea because of the way the vore mechanics are implented. I don't know if Japes & co is gonna be eating people in the main game after this one or if CMCdev is gonna go 5%, but in a 2D platformer, a vore only challenge is totally doable, but here, due to the way everything works, you absolutely want to soften ghosts up before eating them, which generally requires the wand. Maybe start with IH, make Japes starve faster and make any enemy that dies damage you, but don't make the wand useless.