Mimic Champion?
I don't know if this would be insanely broken or easy to see through but would a champion, who can mimic other champions be useful?
I had this idea of a shadow isles demon who took the form of something innocent (Much like 
) to lure people to him so he can kill them.
His ult could be where if he kills an enemy, he can decide if he wants take the form of who ever he killed, the duration of the form (Undecided) is the enemy's re spawn time He could be a very good ganker since the enemy might think its one of their allys coming into lane to help, causing the enemy laner to play more aggressive not knowing that its the enemy. if he recasts his ult on an enemy his mimic form collapses and he leaps at the enemy. The form can also be collapsed upon taking damage from an enemy champion. During this time, he cannot cast any spells excluding summoner spells and his ultimate.
Since the biggest counter of this would be knowing that your ally has died, i had the idea of a passive in his ult called "Silent Kill"
Upon killing an enemy, the announcer doesn't say that an ally has been slain, and their re spawn time doesn't show up. only for the one that has been killed. If he doesn't take the form of the one he has killed within 3 seconds, the announcer states that an ally has been slain and the re-spawn timer will show.
This would bring a whole knew champion to the game, nothing like any other champion. One that can literally trick the enemy. This would be an assassin jungler.
To the enemy, he will appear as an ally. Showing up on the mini map with a blue border, health bar being blue.
For example, if he kills 
his mini map icon will change to lee sin, and to the enemy he will appear as lee sin. But to his own allys he will be shown on the mini map as his original icon
[sg-kiko]
