Kayn and Rhaast by ThexLoneWolf

Kayn's scythe is possessed by a Darkin named Rhaast. At some point during each game, either Kayn or Rhaast will consume the other: evolving most of Kayn's active abilities and replacing The Darkin Scythe passive with a new one. To bend Rhaast to his will, Kayn must damage enemy gods with ranged attacks, while attacking melee gods will empower Rhaast to consume Kayn's body. Once enough enemy gods are damaged, one of two unique items specific to Kayn will appear in the shop, based on which type of god you damaged more. Purchasing this item will evolve Kayn into either the Shadow Assassin or empower Rhaast to become the Darkin Slayer. Regardless of which form initially wins, you can wait a few minutes to choose the looser.

If Kayn becomes the Shadow Assassin, his attacks will deal bonus damage for the first few seconds of combat with enemy gods.

If Rhaast takes control and becomes the Darkin Slayer, he heals for a portion of all ability damage done to enemy gods.

Kayn dashes forward a short distance, then slashes in a circle, both dealing damage. This ability deals bonus damage to jungle enemies.

If Rhaast takes control and becomes the Darkin Slayer, this ability deals bonus percent max health damage to all enemies except minions.

Kayn readies himself, then slashes in a line, damaging and slowing enemies struck.

If Kayn becomes the Shadow Assassin, this ability's range is increased and a living shadow will strike for him, allowing Kayn to move freely after casting.

If Rhaast takes control and becomes the Darkin Slayer, this ability will knock up enemies.

Kayn gains bonus movement speed and the ability to phase through walls. If Kayn enters a wall, he receives a moderate heal and the duration of Shadow Step is extended significantly. The extended duration is only granted if Kayn is not in combat with enemy gods.

If Kayn becomes the Shadow Assassin, this ability grants even more movement speed and Kayn gains slow immunity during Shadow Step.

Kayn infests an enemy god he recently damaged, becoming untargetable. When the duration elapses, or on recast, Kayn jumps out of his host, dealing massive damage.

If Kayn becomes the Shadow Assassin, the range of Umbral Trespass is increased and using it refreshes the bonus damage from his passive.

If Rhaast takes control and becomes the Darkin Slayer, this ability's base damage is replaced with percent maximum health damage and also heals Rhaast heals for a percentage of the target's maximum health as well.