The Kayn build for Jungle is Goredrinker and Conqueror. This LoL Kayn guide for Jungle at Platinum+ on 13.23 includes runes, items, skill order, and counters.
Kayn Counters
50.6%
(+0.3%)
48.5%
(-0.0%)
8.9%
(+1.0%)
10.1%
(-0.7%)
716
(+49)