Not much to really say other than the title. I think anything Warhammer Space Marine inspired would look incredible on Mordekaiser, his armor is almost asking for it. My specific idea is a [Space Marine Chaplain](https://i.imgur.com/wGTfaXY.jpg), who are somewhat of the Chapter's spirit and soul. They are very skilled in melee combat and almost always have hammer-like weapons to pound the hell out of any heretics or mutants they come across.
Warhammer just seems like a no-brainer as far as Mordekaiser skins go and I'm suprised he doesn't have one already.