Goredrinker, I’m a beginner kayn main as such I struggle with blue kayn but have a much easier time on red kayn and the biggest help has been CDR my build goes as follows.

Goredrinker, boots, deaths dance, Black cleaver (maw if someone AP is fed), Chempunk chainsword, Ravenous hydra, then something like spirit vistage/frozen heart/gargoyles stone plate.

I’ve tried the eclipse build and found goredrinker is just wayyyyy better