Overall I think stealth is fine but there a some cases where champions abuse it way more than others. Is it healthy? If not, could it be made a more healthy mechanic if they reworked it a bit, and how? Should they add more counterplay to stealth? (I'm looking at you, Vayne)
Yes.
Players should be encourage to use fog of war, brush, and other stealth mechanics to out-wit their opponents.
Or are you talking about invisibility?
Stealth itself can be healthy but the way riot implements it is not Evelyn is currently the most fair in the way of implemented stealth but she has massive healing for nor reason. Thing is if you have stealth you should take a massive hit to lethality in your kit. (or durability but riot doesnt want to make champions as weak as they need to e because they want everyone to be 'useful'
