I'm sure that Shaco needs some small buffs to be viable.
Like his passive is lackluster, it should convert the damage to true damage on backstabs instead of the pitiful damage increase.
His Q should reset if he kills a champion, that way he can have a chance of survival after killing someone in a teamfight.
His W duration should scale with ranks, like: 60/120/180/240/300 seconds.
His E should reduce the attack speed of champions too and the active should blind them.
His ult clone should be able to cast all spells including the ult, that way shaco can create a useful army of clowns to aid his team.
