Assassins have too many failsafe or handicap mechanics.
In my mind the assassin role (Fighters are also guilty of the same concepts here) should have a lot less safety and even borderline lack of reliability against strong opponents. It just keeps feeling worse and worse playing against the new assassins and even the older assassins at times, and it's painfully apparent that riot doesn't take any real thought when designing assassins as to what counterplay should exist.
Overall we'll never see any real change, but simple adjustments shouldn't be entirely impossible. Right? Various mechanics or portions of abilities that have no necessity and only exist for the reduction of counterplay.
slow immunity while going through walls, whereas slowing a champion is a valid way of counteracting them running at you, kayn just doesn't give a shit when he's running through a wall towards you. Landing a skillshot slow should be a rewarding move for you, but obviously not here.
Instant ult casting really takes his "oopsie" button to new heights when he literally needs a split second to nope the hell out.
Both the apparent 0 cast time and instant full coverage of his wind wall (not to mention that if he casts it last second the direction is irrelevant.) and the handicap time on the knockup-ult interactions have always felt so unhealthy. Having better reflexes honestly doesn't matter half the time because he throws the wall behind him, but it still blocks your ability? ugh.
Her ult still stuns you after a knockup whether she hits you into a wall or not. So even if she isn't playing around the walls, which is a huge part of her kit, there's no functional penalty as she still gets to brawl-beat you while you just sit there and take it.
My ONLY critique on this clown is the clone's instant fear after being killed. That just left such a terrible taste in my mouth after his rework. It's so gross to play against. Well that and the fact that all of his tracking counterplay was removed when cloning as all status effects duplicate so there's no way to track them after splitting.
I can honestly live with most other assassins in their current states as they have pretty well defined, fair, counterplay.
BONUS
~~ Let's face it, she's a borderline assassin these days. How about slows effect her Q's distance traveled? That way she actually gets effected by slows. Eh forget it, rito says no.~~
I'm sure at least one of these resonates with everyone, and please discuss similar issue with other champions you've noticed.