Kayn's Ultimate (and Rhaast's current state in the game)

I don't work at Riot, so I don't know the whole picture, but I have had some concerns with Kayn's Ultimate since his release and wanted to see what others thought about it. There exists a laundry list of things I take issue with in regards to the ability so I will try to order them with some semblance of sanity.

Firstly let's start with the gameplay, as this is the gameplay section.

1. To activate Kayn's Ultimate, you must first damage an enemy champion, marking them for 3.5 seconds, then allowing you to activate your ultimate on them. My issue here has nothing to do with the mechanics of how the ultimate works but rather, a frustration with the amount of time you are given to activate your ult on a champion. Every other ability and item that calculates a champion exiting combat (to my knowledge) is 6 seconds. I don't understand why Kayn's ultimate only lasts for 3.5 seconds if the champion who is running away from me is still technically in combat with my character. I just don't understand the reasoning as to why it doesn't last the full 6 seconds of being in combat.
2. With all the animations, from initial cast, to final second before the soonest possible instant you deal damage upon exiting the enemy champion, is 2 seconds (having timed myself, probably poorly as im trying to smash the R key, click out of the champ and start and stop time on my phone, 10 times ranged from 1.95-2.15 seconds). This means that on top of the prerequisite to damage a target first, you must then wait at least 2 seconds to damage the enemy and I cannot explain how many times I have lost kill gold to either a teammate kill-stealing, or the opponent having enough time to burn heals, shields, and get safely under tower to then try to turn the fight or get away safely. In terms of a getting a kill stolen by a teammate, there have been many times it has happened, after I activated my ultimate, but before I infest the target champion, and my ult will go on a 2 minute cooldown for doing absolutely nothing. This is my second issue with the ability: the infestation isn't immediate, it takes about a second to become untargetable and then you have to wait to deal damage and even if you don't infest the champion, you still end up on cooldown. I guess I am just wondering why a single target ultimate, with a 2 second delay to damage, that brings no crowd control or major team fight advantage to your team, gets a 2 minute cooldown if it doesn't go off yet Tahm Kench gets his ult put on a 10 second cooldown if he is damaged at all or even accidentally walks while channeling.

Second topic I wanted to discuss in terms of Kayn's Ultimate is small but aggravating, I don't know what to call them but for lack of a better terms I will call them "target indicators" (they show little lines telling you there's a shortcut you can take to a target (Ivern Q, Thresh W, Yasuo Ult, Kayn Ult). I have no problem with it being visable, but they are bugged and will show up while your ultimate is still on cooldown, preemptively marking enemies with your ultimate's passive before it is off cooldown, effectively telling the player "You can use your ultimate!" when in reality, you have 3 seconds left on your ultimate's cooldown and there's nothing you can do to use it, the passive timer is just off cooldown saying "in the next 3.5 seconds, you can use your ultimate on this person." Little thing, maybe it's only me with this opinion, but this is extremely aggravating in my opinion.

Final topic I wanted to bring up here is Rhaast and his current place in the game because my god, preseason feels like it neutered him so badly. I haven't seen a good keystone rune or path to take that feels effective in the jungle, I haven't seen anyone who plays Kayn, go Rhaast, and I think it is because his passive makes no sense to what he is "marketed" as. When Kayn was released it was said he could either be played as a tank or an assassin but the way his passives and damage scaling's work, building tank doesn't help him at all. Rhaast still needs to build damage because all of his abilities scale off AD including the heal from his wall-walk. One would think when you choose the tank route, your abilities would scale off of bonus health or something like that and contrary to what one would think, it's not. In combination with that, Rhaast's W knockup lasts as long as his animation and where his ultimate doesn't have enough range to target enemies from the tip of his W skillshot, and with that combined with the problems with his ultimate from above I think that really screws Rhaast and that's why he is in such a terrible spot. Shadow Assassin Kayn doesn't have to stop to use his long distance poke (with W) as well as a slow immunity and a 70% bonus movement speed allowing him to ult any target he chooses with ease, and where Rhaast lacks a way to catch up to his prey that is escaping, I think that's why Rhaast is in such a bad place.

The only other problem I have with Kayn's kit entirely is that the damaging line in his Q is farther back that his damage taking hitbox, so when you dash into an enemy that is dashing into you, you will always die, with no trading ever. It is so frustrating dashing at a Yasuo with 10 health and he dashes at me and he gets to walk away every time..

Just wanted to put my opinions out there and wanted to see what others thought. Sorry if this is kind of rambling too. Much love, board-go-ers!!!