We have a "soft" stealth option for long-term combined with a tactical skill you can use sometimes and it's been interesting. Less problematic;

Essentially, stealth makes you 100% invisible, but imagine all champions have Oracle's. What this does is makes it so your engagement range and such are the same, but you can scout, use it strategically or set up good positioning with it. Obviously, kits would be adjusted to utilize this.

I'm not 100% sold on this currently, but it's definitely the best-testing solution we've had. It's a tough problem in a game where information has such a premium.

I could be wrong, but this sounds a lot like WoW's rogue/druid stealth mechanic. Would you agree? From what I gather, Blizzard's balance team has never been satisfied with it, so I doubt it will be panacea in LoL. However, a small improvement might be better than none at all.

Vlad?

The range is much longer in the version we're using - so it's impossible for the stealther to get up to you invisibily and engage without you having time to react first. They also use a facing mechanic that changes the visibility range.

My favorite stealth so far is in TF2, but those mechanics translate really poorly because they're balanced by a first-person view, area-projectiles being common, and collision.

Except MF isn't a decent carry anymore. The only viable carry picks are Corki and Ashe. Corki will always have more raw damage and mobility than MF ever will, I mean, he has a dash/escape mechanism, she has her crappy passive that gets turned off if she gets hit by even a minion, and not even some noticeable raw damage to make up for no having an escape mechanism.
Ashe, on the other hand. Best ranged carry ever to exist. CC, permakite, permaslows.

I think you should focus on balancing ranged carries for next patch... either nerfing the top 3 or buffing the rest, any carry below Ashe/Corki/Urgot is **** at the moment.

And apparently Xin Zhao.

I mean it's amazing to see someone nerf a champion no one has complained about in months out of nowhere

Still I think you guys do a good job for the most part

Garen.

And Pantheon.

Ah, yes, I see what you mean. I must assume, then, that minion vision would not reveal stealthers?

Side note: TF2 is an excellent game, but I think the spy's ability to arbitrarily disguise himself is even more central to his kit. In LoL, that can't work because players can see all their teammates on the minimap, and there's no class duplication. That said, resource drain (mana/energy) during stealth (like the default spy watch) could work instead of a fixed duration.

Stealth rework:

-Grant CV stealth detection of heroes (not wards) if u wanna go for a kill call for a scan of the area with CV
-Change Stealth to 100% invisible as long as hero dont move... but if he move the stealth amount is reduced ...enemys cant click on you or cast target spells on you but they will know if u move arround
-Add a mastery that reduce the gold price of wards (not much)
-Add new summoner spells low cd animation of corkis phospor spell add bit of damage and allow to destealth heroes

@Morello

Stealth Idea:

- While stealth champions are stealth they can only be seen when the opposing champion is facing in the direction of the stealth champion.(course have a decent range on it and Oracles can still do what they do now, aoe detection) Stealth champions having to stay behind or out of line of sight rather, of other champions while stealth to avoid detection. Give stealth champions a slight damage boost on one of their abilities when attacking from behind while stealth and slight increase in movement speed to get to their target faster while stealth. Making them slightly harder to play and require more skill to play. With teamwork a person can distract an enemy champion and a stealth champion comes in to help or for a gank, as well as timing when to strike(like a assassin right?). But at the same time a player can avoid this by looking in the direction as where the stealthy is or the usual tower hugging, oracles for an aoe detection, and called mias. Did a few normal games as eve to test out on how difficult it would be to avoid detection by staying behind or on the sides of real players, honestly its easy for me. Of course it didn't really matter because the other team couldn't see me even if i was infront of them. So im wondering how players would react in games if they had the ability to see stealths infront of them. Would be fun if i could test that out