Fryguy

I have a player who wants to create a character similar to Mystique except this character touches her target she is not only able to mimic their shape, voice, retinol, signature, fingerprints, etc  she is also able to copy their powers. Similar to morph from the old silver age ex man, his shoes, and the animated cartoon.  He wants to use multi form, but the rules are more deformed not exactly apply in the situation. I suggested we come up with a custom adder to make multi form “cosmic“ but I’m not sure how much that should be. I welcome any suggestions to making this character. One last thing, we use 5e, but I can reverse engineer 6e.