Kayn vs Master Yi Jungle Matchup

How to play as Kayn

Avoid an isolated duel with Master Yi before form; look for a skirmish with teammates, and punish only after he uses Meditate(W), when it can no longer reduce Umbral Trespass(R)'s damage.

Master Yi's Alpha Strike(Q) makes him untargetable during its dash, while Kayn's Blade's Reach(W) is a line attack; a timed Q can avoid Kayn's main setup.

Meditate(W) reduces incoming damage, so it can blunt Kayn's Umbral Trespass(R); if Yi spends it on an auto attack reset, that defensive window is gone.

How to play as Master Yi

Hold Meditate(W) for Kayn's burst instead of spending it on an auto reset; Kayn can threaten Umbral Trespass(R) once you have used the damage reduction.

Sources

These notes come from r/KaynMains, checked against the champions' abilities.