I fully expect this to never be made (like most hero ideas), but the idea was so interesting to me I just couldn't let it go.
So the idea for the hero would be for it to be a large (Orksbane size) with a black panther or gorilla/monkey king look to it. The idea being copycat or aping or monkey see, monkey do type shenanigans. It would also be a melee Hero, not a ranged one.
For simplicity I'm going to use Copy Cat for the name of the Hero, but any of the three works for this idea.
In effect, Copy Cat completely copies the first Enemy Hero to come into their range (no copying friendlies). Copy Cat will then maintain that copy for the entire battle, no changing (so strategy can play a part by forcing it to copy a useless skill or a really good one).
Copy Cat retains its own appearance and stats, but gets a copy of whatever skill the Enemy Hero has. The copy of the skill is at whatever level Copy Cat's skill is. So if Copy Cat's skill is level 10 and the Enemy Hero's is level 4, they still get the skill at level 10.
When Copy Cat procs, they get the visual effect of whatever skill they copied (so a PD copy would have pumpkins above their heads, Santa Boom would have him sending out exploding rockets, et cetera).
In terms of stats for the Hero, that would more depend on which version used.
Copy Cat should probably be relatively fast in movement and attack speed, while probably more average in hp and slightly above average in terms of attack power.
The Ape King should probably have more attack power and HP and maybe be more average to slightly above average in attack and movement speeds.
The Monkey King version should probably be slightly above average in all, sort of an all around good, but not necessarily great in any one area.
Also, just to be clear, I'm not suggesting three different Heroes. I'm suggesting one Hero with three possible looks/stat packages, all with the same Skill... the ability to copy one Enemy Hero's skill for the duration of the match.
Move along, please.