Treat the orb bar like a routing resource: take early touches only when they speed up form without wrecking your clear, because base Kayn that is still untransformed after 20 minutes is in terrible shape and Rhaast is much more forgiving than blue when the game is even or behind
Live in the wall—chain E from wall to wall, use thick terrain to shorten Q, and on blue form start with W from terrain instead of stepping out early and turning yourself into a normal melee target
Choose the form by which champions you can keep touching: Shadow Assassin for brief access onto slippery carries, Rhaast for fights where bodies stay in range long enough for repeated Qs, W knockups, and healing to matter
Go blue when the game is decided by whether you can repeatedly reach one slippery carry from fog or walls. If the enemy damage sits on ranged, mobile, or low-health champions and fights keep breaking apart before anyone stays in front of you, Shadow Assassin usually gives you the cleaner game. Stay red when the champions deciding fights are the ones forced to stay in your space—bruisers diving in, tanks frontlining, melee carries brawling where your Q, W, and healing keep mattering. The quick check is simple: after the first clean touch, which form still lets you keep hitting the champions that matter?
Kayn wields an ancient weapon and fights Rhaast, the darkin within it, for control. Either the Darkin will triumph, or Kayn will master Rhaast and become the Shadow Assassin.Darkin: Heal for a percentage of spell damage dealt to champions.Shadow Assassin: For the first few seconds in combat with enemy champions, deal bonus damage.
Kayn dashes, then slashes. Both deal damage.
Kayn damages and slows targets in a line.
Kayn can walk through terrain.
Kayn hides in an enemy's body, dealing massive damage when he bursts out.