This build is legit insane. The ability to go faster than anybody has ever seen a Kayn go (and yes, it could go faster with a tank blue build, but that's troll), only to get cc'd by an assassin that does bonus damage when he hits for the first coup[le seconds. It makes every combo a free one, and once you start one shotting, there is no hope for the enemy team whatsoever.
The main thing with this build is the predator everfrost combo. Morgana used to do it to hit her Q, but she has never had the burst that a AP Blue Kayn has, and that just makes it scarier. Even if you can't oneshot, the threat of having a super speed assassin coming at you with an AOE cc is frightening so say the least. After you hit everfrost, you want to W and auto, then Q and auto, then do whatever. This will get the maximum value from your lich bane, and make sure that they know you're a good player.
If they try to flash your everfrost, simply disengage. Going Ingenious Hunter helps a lot with this, as it means you can active your everfrost and predator even faster, and kill even more people with your insane movespeed. I know it sounds completely troll, but just wait until you try it, it might be even stronger than a Blueser Kayn build.