The counterplay of certain champions.
Okay... So... As far as I know, counterplay is a big part of league of legends, right? A lot of champions have openings that, while not necessarily easy to take advantage of, are easy enough to notice the gaps in order to take advantage of. There are, however, a few things that, while they definitely have counterplay, I feel is way too biased towards, having the right team comp, or the right champion/champions in order to take advantage of. This, specifically, is stealth, in my opinion. (And maybe Illaoi, tho that might just be me being bad at the game or smth, feel free to shit talk me in the comments about getting good at the game). So... Stealth has a few ways to be countered, using a sensor in order to see where they are, and using abilities into the air and if they hit, they will blink slightly, then there are a few champions with abilities that make invisible champions visible (Thresh q for example). The problem is: while censor might be able to tell you where they are, you still won't be able to hit them, and what happens when they get the jump on you? Most stealth based champions are assassins or champions with a lot of dueling potential (Shaco, Akali, Vayne, etc.) So then, unless you're able to keep your eyes open for their existence 24/7, then they are likely to at least, once, get the drop on you, your carries, whatever. Even then, I've once done everything in my power to counter a shaco, but he was still able to avoid me till his stealth came back up and then one shot me. While this might perhaps not be a big issue in platinum and up, I feel that while you shouldn't make those kinds of champions completely unplayable in higher tier play, you also shouldn't make it so that, if you end up against someone that knows how to effectively use stealth, you're completely unable to do anything about it. Of course, then there is the option of having your cc champs wait around for the enemy to try and engage with stealth and then cc lock them making them unable to do anything. But when they reach a point of being able to kill your carries in a second or less, then how are you supposed to deal with that?
However, this leads me on to another point I feel this game should have: the ability to counterplay a champion with any other champion, to at least some extent. Of course, assassins are always going to have the advantage over adc's in a 1v1 fight, but adc's still have tools to counter the assassin from one shotting them, same with mages (Zonya's as an example), when it comes to stealth, what is a nunu supposed to do other than try and charge up their ulti or run away? What about someone like vayne, who can't do anything if she doesn't have a target? (Don't get me wrong, I also feel her stealth can be way to overwhelming in a lot of situations), I remember when pink wards could show stealthed champions. However, I also feel that, that is the wrong way to go about it as well, since control wards (the new-ish pink wards) only cost like 75 gold, if dealing with stealth you could just keep 2 of them in your pocket, place em when you need em, and then the stealth doesn't do shit anymore. Instead, I feel there should be an item that gives true sight, something any champion could pick up, something that you wouldn't necessarily pick up if there wasn't stealth in the enemy team, however, an item, perhaps worth like 2000 gold or somewhere around there? Something with a short cooldown, that allows you to deal with stealth, at least every team fight, if not a tiny bit more often, at least once.
Anyway, this leads me onto Illaoi, what I feel is probably one of the most dominating champions if you don't have the right tools to deal with her. The counterplay for Illaoi is supposed to be that she can't do anything if she's not next to her tentacles, but that isn't entirely true, is it? She can just use her e, and that will seriously chunk the opponent if they don't run, and if they run, they are losing out on a serious amount of lane pressure and maybe even experience and gold. So then, just fight her and lower the duration of the e! But that doesn't work all that well either, as Illaoi has damage, is somewhat bulky and has % healing on top of all that, not to mention that if your melee and fighting on top of your clone thing, whenever those tentacles slam down, you're taking damage both yourself, and through the soul, leading to her damage becoming even higher than it should be (I could be wrong about this one, though all I know is that every single time I've tried to trade an Illaoi after having my soul pulled, I lose the trade by quite a large margin) Of course, if you have range, then she isn't much of a problem, just keep your distance, pelt her with autos and spells, and she won't be able to do much back to you, since you won't ever be close enough to her tentacles for them to be an issue. But not everyone knows how to play ranged top laners, especially since there are so incredibly few of them, versus the amount of melee top laners that there are. So for those melee top laners, or, more specifically, at least duelist top laners like Fiora, Riven, etc. All they can really do is sit back and hope Illaoi doesn't hit her e, and pick up the remnants of their farm by the turret.
Anyway, those are my thoughts on some of the mechanics in the game currently.