What if there was a champion that could copy or reflect other champion's abilities?

Has someone ever thougth of this idea? Although seemingly bland, I've never actually seen anyone posting this.

For example, a champion that could copy the amount of damage that the last ability of a champion did, and then reflect back as magic/physical/true damage.

Or a champion that could reflect projectiles, kinda like Yasuo's wind wall but instead of simply destroying the projectiles, that champion could reflect them back. Of course such ability would have to be an ultimate or have a really long cooldown, otherwise it would be too powerful.

Or an ability that could use an ability that could tag another enemy champion and then copy that champion's ultimate.