Rather then calling him,"Master of Metal"

Why don't they call the,"Taskmaster". They can keep most of his current theme and style but have his identity focus a bit more around his ult and the concept of enslavement. Allow Morde the ability to use his ult to enslave the souls of both champions and jungle monsters. When enslaved there is a faint drooping chain, that might look similar the kalista's pact thing, that connects mordekaiser to his enslaved minion. Using his ult on a jungle monster might provide morde with slightly less then previous, but could potentially provide team wide effects while pushing.

Example - Using the ult on Golems would provide a ghost of the golem to tank damage and attack where told until the ability wears off. However, it could also provide a slight boost in mana regen for allied champions that are within its radius. The regen provided wouldn't be anything to overpowered and would only last for the duration of the spell or until the ghost is killed.

Using the ult on Brambleback would provide similar effects except that instead of mana regen, allied champions fighting close enough to the beast would be able to deal a very slight burn on their auto attacks.

Using the ult on a Krug would provide a slight buff to armor. Razorbeaks would increase vision. Wolves would provide a slight increase to movement speed. And the current version with dragon would remain mostly unchanged aside from the fact that morde would have to actually use his ult on dragon.

This is a really rough idea and would need alot of work. I totally understand that the power ratios and numbers would need to be changed and balanced in order to make his kit more fair. Overall I really like the idea of champions having a very clear identity. I see Mordekaiser's ult as enslavement of the soul which would work well with the idea of an Underworld Taskmaster. It would also allow him to be a better team fighter so that his current numbers could be changed to be a bit less snowbally. I think it would also be nice to be able to self cast his W and perhaps the change to a more team fighting Juggernaut would allow them to reduce some numbers so that he can have that ability back.

Let me know what you think, and understand that this was a very quick and rough idea.