Mokujin from Tekken series.
his skillset changes randomly to a current champion's skill set every game you play him including the passive.
ofcourse, he'd still look like wooden blocks and logs except with the animation of the champion he becomes at that game. i.e. wooden orianna with a wooden sphere.
this guy will be the true random character. ofcourse it wouldn't stop having the improbable chance of having 2 heroes with the same skill set in the same game in the same team. -- 2 kayles in the same team? double the ultimate. with the amount of heroes in LoL, it will be very rare.