Terook, the copy cat.

Basic idea: Terook is an alien like melee champion that steals the abilities of other champions to build his own kit.

Kit: Q = [Q from other champion] W = [W from other champion] E = [E from other champion] R = Terook extracts DNA from an enemy unit dealing 45/65/85 physical damage (0.8 AD) and 30/50/70 magic damage (1.1 AP). If the unit is an enemy champion, Terook may copy an ability of that champion until death. The copied ability he takes will not copy duel powers {ex: won't copy shyvana's dragon form abilities}. (cost: 35 mana) (cooldown: 10/8/6 seconds) Passive: Terook steals 4% of enemy champion's current mana every auto attack. He also steals 4% of a monster's current health every auto attack. (no effect on Baron or dragon)

Why he's not OP: Having a champion you can build sounds crazy op, but there is more to it. Every champion is built around their kit. Without a champions passive or ult, most champions fall short. Those two important things are the two things that Terook can't take. Every game, the summoner must analyze the enemy team and decide what abilities will do him the best for that game. Making each round unpredictable, but fun. Stealing abilities like rengar's Q would be great, except for the fact that Rengar's kit is made around his Q so that he can landed it effectively. Terook can only steal one Q from one champion at a time, thus no worries about a Rengar's savagery and Nidalee's Javelin toss combo. When Terook dies he loses all his copied abilities. Meaning he'd have to travel across the map to reclaim his home made build. Early game this wont be so bad, but by mid to late game, running into any enemy champion with only his ult at hand is bad news. I honestly think he might be too weak. That's why i gave him such an interesting passive to help give him a little bit of an edge.

Designers notes: For the designers of league, making a non-buggy champion like this sounds like a nightmare, but i do think there is a short cut to be made. Whenever using a copied ability, terook can simply turn into the champion he is copying until the ability is completely over with. It seems like a cheap way out, but honestly i think it would be cool. It could even help during a team fight to confuse enemies. Just a thought.

note: I made Terook to be open to players like you so you can add your own champions concept art designs or small changes to help balance him out. Heck, I'm up for a cooler name if you have one. All are welcome to bring him to life.