League needs a mimicry mechanic. New champ time!

We need a champ who can use moves used on them. Maybe this can be their ult, maybe a couple of skills based off this, maybe one normal skill for a normal ability and his ult can be using the last ult used against them. Maybe they just get some random skill from someone in the game or maybe even a champ that isn't even on the map. However, League is way too old and has way too many abilities for us to be unable to copy someone else's moves. It's super complex, has counterplay potential, and requires decision making, which are three things Rito craves, right? And it calls upon a unique champ identity: stealing identities. I can already see the blank face with the white robes and dead eyes, searching for someone to steal from.

Now of course there has to be limits. For example, if they copy Nasus' Q, it would have to either be pernament for the rest of the game, have the same number of stacks as Nasus has, or just ignore the passive and do base damage. But these are decisions that I won't go too deeply into, because apparently Riot can't use fan ideas.