Any chance that Natalie's assosciated transformation will be changed in the future? It's too easy to reach D-Rank without using this that there is no point in giving that trait. Maybe you can have it set so that if you have already achieved Succubus Shift, the Mimic Core grants a change to your Succubus Shift, either a wing change that matches Natalie's wings or the ability to turn on/off a futa ability?