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.