Ever Considered a Stealth Mechanic SImilar to the Wraith from Dead by Daylight?
If you're unfamiliar with the game, the Wraith is a character that can toggle into and out of invisibility at will. The downside is that doing so is a channeled ability during which you can't attack. The main tilt point with stealth mechanics is that they allow the user to get into range to attack and generally deal some damage before the target is able to react. It's sort of a guarantee that you can land an ability first. This gets very frustrating to face since the types of champions given stealth are usually the kind that can also kill you as soon as you see them. Forcing an uncloaking delay allows stealth to be stealth, preserving its uses for scouting, positioning for flanks from unexpected locations, and for escaping while giving keen eyed summoners in team fights the opportunity to capitalize on that Evelynn decloaking as a fight starts. This is just a mechanic I'd be curious to see in general, maybe on Eve. Giving her perma invisibility but limiting its use as an engage tool.