Here are my suggestions for potential 'nerfs'
Option 1- Nerfing the early
W slow shouldn't throughout the whole thing. Instead have it slow on first impact.
Option 2- Stealth Nerf
Increase his detection radius on his stealth Just little of his base auto attack range.
Option 3- Out of stealth Nerf
make it that the first auto out of stealth deal only 80% of the initial dmg (Or make it so that It Can't Crit even at 100%)
Option 4- The core problem Item
Nerf
radius ( much smaller cone) <--Not just nerfing twitch with this; but I see this as the route of the issue(IMO) (crit Being the bigger issue)
adc's Are REALLY good in team fights. Giving them AOE/Wave Clear and special interactions makes them feel to strong.
Option 5-BlitzCrank Strat
Have this Ambush slow you movement speed by 25% when you get out of stealth.
(I personally do not like this, but its still option)
Option 6- Smelly
Have a singed poison like trail that you can see even in the fog of war(as long as your inrange to see it) while hes in stealth (doesn't deal damage)... but
Option 7- Some crazy shit
Make it that his autos deal less damage. like by a lot.
And make it that so the more stacks that they have the more damage his autos will deal.
(So at the 3rd stack he will do avarage damage.)
And when his E is on Cool down, he can't add anymore stacks on any other target.
(and to maybe have it worth Pressing E, When you press E the true damage will Deal double the damage, and expires faster.