Stealth: Why not alert characters of nearby stealthers?
But not actually reveal them.
Rengar's ult is a good example of this. You can't see him, but you know he's around.
You get the yellow warning Exclamation over your head if:
- A stealthed enemy is within a certain distance (a screen seems about right, less if you are already in combat)
- They are in a visible area of the map (not fog of war or unwarded brush)
The exclamation wouldn't say how close they are and it wouldn't reveal them in itself. It just implies "look out, get ready".
The lowered detection distance while in combat means there is a clear time when stealthed champions can capitalise. It also means that sneaking up on someone out of combat needs good use of the map to not alert them too soon.
Doing this would make stealth less powerful in a surprising sense. You can drop pinks when alerted or sweep for them. But it would allow stealth to be healthier overall. Eve wouldn't need the nearby-reveal on her passive for example and a champion's other abilities can be tuned knowing that the enemy will generally know they're around, just not where, rather than tuning them to the assumption that you are always able to surprise them.
It would also mean that normal wards can detect their presence by extending your visiblity, but not actually reveal them to you.
A detecting player is the only person who see's the Exclamation over their head. Similar to Eve's passive, the stealther would have a symbol over the heads of those who have detected them (maybe an eye or something?).