Why does Shaco need execute damage?
The dude already stealths around and can easily get onto low-health targets, why does he ALSO need an execute on top of that? It's oppressive as hell because it basically mean you just CANNOT be in lane with low health EVER, which makes him a total pubstomper because they're too stupid to realize they need to BACK OFF or they're dead. Remove his execute damage.
R: Deals additional missing health damage even though it scales infinitely
W passive: Deals additional damage to enemies below 30%