[{quoted}](name=L Psy Kongroo,realm=NA,application-id=3ErqAdtq,discussion-id=OOuGgoqt,comment-id=0000,timestamp=2019-10-24T00:59:25.199+0000)
Don't exaggerate; his Q is a much longer cooldown than that and you know it.
Also, what assassin CAN'T 1-shot a carry when they get ahead? That's kinda their entire reason for existing. If the carry doesn't get 1-shot, they'll just be healed and shielded by the ward bitch that always stands around them, then heal back to full in 3-4 autos because lifesteal. Fights don't last much longer than 2 seconds to begin with, so if Shaco can't kill someone within that amount of time, he's useless. Meanwhile Rengar can leap out of stealth after running half way across the map and 1-shot a carry in .5 seconds, but no one seems to care. Oh, you're gonna mention that indicator you get when Rengar is nearby? That one whose only purpose is to inform you of your imminent demise because there's absolutely nothing you can do about it (unless you're a mage with good Zhonyas timing)?
Shaco is strong, there's no denying that. But let's not pretend that the box nerf didn't fix the thing that was ACTUALLY making him busted: the near-instant level 3 clear into an unavoidable gank.
The problem with Shaco is that there's no opportunity to kill him when he shows up to one shot the carry. Kha'zix has clear counterplay: his assassination is tied to his long cooldown ultimate and he needs isolation. Rengar normally dies after assassinating his target.
With 30-40% CDR, you only have a 3 second window before he can Deceive away. He can repeat this forever, only being vulnerable for a short period each time, and still doing his full burst combo. If he has his ult up, there's virtually no window between juking the CC/burst with it and figuring out which one is real, especially when you don't have visual indicator to denote the real one. If you're relying on melee for peel, they have to gtfo before the box pops, further cutting in to the time you can interact with him.
The stealth just needs to be gutted so he isn't so incredibly safe. His early gank is the least of the problem.