Ulti idea
It'd probably best on a new champ, maybe a Dr Frankenstein or Yuri [C&C RA] styled character.
Basically it should be called something like "mind swap" whereby the target character should effectively swap view and control of champion with the ~nearest or random other champion for ~2 minutes. With some slight hazed aura around the edges to help with some of the confusion.
It would seriously mix things up [and be mechanically possible?] but the much of the impact could be mitigated thro player practice and skill with some possible leftfield consequences.
G