TL;DR Make Alpha Strike untargetability less long.
When Master Yi uses Alpha Strike, his untargetability duration depends on how long it takes for the animation to finish, which depends on how many targets he strikes. If he uses it on a single isolated target, he's untargetable for only 0.25 seconds. If he uses it on an enemy in a minion wave, he's gone for almost a full second.
Alpha Strike serves a few different purposes. Gapclosing, defense, damage. When I use Alpha Strike, I only need to be untargetable long enough to do two things:
1) Dodge the spell I meant to dodge
2) Follow an enemy who is dashing
Being untargetable longer than that *doesn't help me* because it delays me from attacking, and my enemies are just waiting until they can fight me again. It also wastes time on Highlander. A four-bounce Alpha Strike is annoying on both sides. To dodge a spell on purpose, I only need to be untargetable for about half a second. If I use my Alpha Strike too early, I should be hit by the spell I meant to dodge, but a four-bounce Alpha Strike is very forgiving. Following dashes is a little more finicky since unlike Warwick's Q, Alpha Strike does not wait for the target to finish their dash before completing. Alpha Strike just drops Master Yi wherever his target happens to be when the Alpha Strike animation is done.
So, my suggestion is to make Alpha Strike more consistent. Instead of being untargetable for 0.25-0.9 seconds, it should be maybe 0.35-0.65 seconds. And maybe it could work more like Warwick's Q with respect to dashes.