Karthus Rework Concept

Passive - Catharsis Basically the same as live except live E is removed as an ability and only activates along with passive.

Q - Fragmented Desolation Basically same as live Q, except when it doesn't hit anything, fragments remain on the ground. If it hits a target with fragments nearby, the fragments then strike the target for a small amount of damage.

W - Soulgate first cast: champions who pass through this gate for the first time will have their soul stuck on the other side. The further a champion is from their soul, the slower the champion moves. A champion may recollect it's soul 3 seconds after it is pulled out. second cast: the soul gate shuts, freeing the champions of their souls, karthus gains movement speed and adaptive damage based on the souls freed.

E - Quoir Unending Passive: Any creature that recently dies around karthus becomes a rooted Singing Soul. Singing souls are long lasting though karthus can only have a certain number. Creatures that stay in the radius of a singing soul for a prolonged time will take damage. Active: Karthus frees all singing souls. They chase down nearby champions for a short while before disappearing.

Ultimate - Requiem Passive: Life's Toll Champions who reach <20% health gain a stack of life's toll. (life's toll gained like this has a 30 second cool down) Champions who survive karthus's requiem gain stacks of life's toll (1 if they are almost full health, 2 if they are approx half health, and 3 stacks if they just barely survived) Champions who cross soulgate, gain 1 stack of life's toll (once per soulgate). Champions who take damage from singing souls gain one stack. Champions who kill karthus gain 3 stacks of life's toll. Life's toll resets if the champion dies to anything except execution.

Active: Death's claim Similar to live ult, except scales hard with death's toll. Also champs with a certain death's toll stack will be executed regardless of their health.