Hmmmm... It is a cool power, but I think it could use some limitations/drawbacks. A fellow mod brought up how it'd be basically uncounterable if used creatively enough. She could drop in, stab someone, and activate her power, no one would be able to track her, and only a sneak attack could prove useful against her. I know you don't really make characters to fight and all, but the idea is a bit OP. I would suggest adding some drawbacks/limitations. The monster hunting her would be a good drawback, it'd force her not to stick around in place too long while a ghosty ghoul. I'm fine with it either way. I'd also suggest that she isn't completely undetectable (Perhaps her outline can be seen if someone looks close enough).