Said it in other topic, will copy paste here:
The thing is: He has a really easy way to proc
at the same time, resulting in an obnoxiously huge burst of damage.
Basicly his Q goes from 116+72,5% AP to 484.55+162.5% AP (with an extra 180 + 10% AP from Thunderlords - 664.55 + 172.5% AP). And this happens instantly. With his core AP build
he gets 567 AP. This translates to a 1643 damage burst happening instantly out of stealth on his Q alone. Without Thunderlords, Lich Bane, Runic Echoes, and Gunblade damaging passives/actives, he'd deal 527 damage on his Q.
Dealing more damage with his Q means that his E will hit harder due to E's 8% missing health damage.
's numbers are not the problem, the items are not the problem, the main problem is how easy it is for Shaco to use those items to their fullest potential.
Shaco was always an item abuser (with Q+P+IE Statik Shiv would hit for a whooping 388 damage before his rework). The only problem is that AP items are much more abusable than AD items because, in theory, they would be a bit harder and conditional to apply.
I'm honestly scared of what will become of Shaco because unless his main playstyle is reverted to AD, he will have to get Olafed/Aziered/Kalisted/Aatroxed very VERY hard.