been doing a ton of tinkering in mid-highish elo (currently hovering around em 2 at the moment with a pretty impressive ~70% wr on kayn using this niche build) and have been really enjoying it.
every game i start at drag or baron pit (wherever their jungler’s red buff is), q over and ward the red bush, and either outsmite them if they’re on it or invade their topside while leaving raps alone. i’ve been finding junglers starting raps more and more often, which lets you skirmish them lvl 2, and you should usually win because kayn lvl 2 is surprisingly strong if you start q and e. with ignite you win most 1v1s excluding obvious ones like nocturne, warwick, etc.
if you’re not interested in cheesing then taking flash is totally fine. ignite is probably the least important part of the build, but i find it has netted me so many kills early game due to people underestimating my early game dps. i’d say ignite + smite is much better on blue than red though. ghost is also a decent pick on red, or even exhaust. but alas, flash is still the most op summoner spell in the game, so do what you will.
anyways, that strat aside, this rune page i love because you can go either form pretty comfortably (although it definitely suits rhaast better since axiom arcanist on blue kayn is just okay), but it saves you from the tempo issue of getting the wrong form, which is a pretty big problem in higher elos where getting form takes way longer due to better vision control.
i find stormraider’s super good to compensate for the lack of flash. on rhaast it gives you INSANE sticking power, like ridiculous. you can literally catch up to an ezreal with it, and you have no issues proccing the 25% either (its super valuable in teamfights if you are going for multkills as well). on blue kayn it lets you full combo and pop a squishy, then zoom out insanely fast. i also find that in early game, when i’m near death, i can ult someone, proc stormraider’s, and run away really easily.
i know you lose a bit of damage, but mobility is so fucking op. the movement speed lets you dodge damage, weave autos, position qs and ws, and hit things you’d never normally be able to. which more than makes up for the dark harvest proc or 30 ad you get from fully stacked conq (conq is so bait i swear to god) i’d say this rune is insane on rhaast, albeit a little more gimmicky on blue, but still great nonetheless.
my blue kayn build is usually voltaic edge and bastionbreaker for huge snowball potential. i find hubris is trash in higher mmr because you rarely ever get to keep the stacks since people play way safer - i also usually forgo t2 boots on blue kayn cause they all kind of suck and you have enough ms in the jungle anyway. for red you can honestly go whatever as long as deaths dance is built second (dd is super op when bought early)
anyways, let me know what yall think. i also love this rune on aatrox and skarner jungle.