Kayn Guide

Key Insights
Kayn can become Shadow Assassin by damaging ranged champions or Rhaast by damaging melee champions.
When Kayn is near enemy champions during
Kayn
E
, a visual indicator shows up on the wall.
Kayn
E
's duration is reduced to 1.5 seconds if Kayn enters combat with enemy champions. Auto attacking or being hard CC'd ends it.
Strengths
Spikes upon acquiring a new form.
Rhaast excels at skirmishes and teamfights.
Shadow Assassin excels at finding picks and all-ins.
Chilling Smite can be used to enter a target with
Kayn
R
for safety in a pinch.
Rhaast is best with items that enhance durability and healing.
Shadow Assassin is best with items boosting burst damage and mobility.
Weaknesses
Is naturally weaker without a form.
Needs to constantly land his skillshots or he'll have significantly lower damage output.
Significantly harder to play from behind.
When playing as Rhaast, any form of Grievous Wounds hurts Kayn because of how much healing he has in his kit.