Passive: Iron Man
Mordekaiser gains a shield whenever he damages an enemy champion(increased charge for killing them) with an ability or kills a minion or monster. Shield generation is increased when Mordekaiser is low on health. Mordekaiser takes reduced damage from auto attacks while his shield is up, doubled against ranged auto attacks.

Q: Mace of Spades
Mordekaiser channels for up to 3 seconds, slowing himself initially but building speed over the duration, then swings his mace in a line. The first enemy is damaged and knocked back, dealing increased damage to all enemies they pass through. If they collide with terrain, they are stunned and take the same damage initially a second time.

W first cast: creeping death
Mordekaiser summons a swirling vortex around either himself, an allied unit, or an enemy minion. Enemies caught in the vortex take damage over time and enemy champions have their resistances stolen by Mordekaiser. If cast on an ally champion they are shielded for a portion of Mordekaiser's current iron man shield and take a portion of the stolen resistances. Creeping death takes more resistances and builds more shield when Mordekaiser is low on HP.

W second cast: harvester of sorrow
Upon creeping death's duration reaching its maximum, recasting the ability, or the unit it is cast upon dying, the vortex closes dealing damage and healing Mordekaiser for a portion of his missing health based on how long the vortex spun before closing plus a flat amount for every enemy champion hit.  If the vortex was cast on an ally champion they will receive a portion of the heal.

E idk I don't listen to metal:
Mordekaiser's next attack does bonus damage and causes the target to bleed. Auto attacking the target again before the bleed expires refreshes the duration.

R still don't listen to metal sue me:
Passive: Mordekaiser gains a small amount of attack damage based on his missing health
Active: Mordekaiser channels, shrouding an area of the map in darkness, causing enemies in the shroud to become nearsighted. Upon completing the channel Mordekaiser teleports to the epicenter of the shroud, dealing damage to and fearing enemies around him (very small radius, ideally would only damage enemies that could see Mordekaiser despite their nearsighted debuff)

Interrupting the channel both immediately lifts the shroud, cures enemies of nearsighted effect and puts ult on full cooldown.