I just took a quick 15 min to think up ideas that might be interesting.
**Magnet's, how do they work?** Mordekaiser can target an enemy and give him a magnetic attraction. If they run toward each other, they get +Ms, if they run away they get -MS. The closer they are the stronger the effects. the -MS includes mordekaiser, cannot recast to turn off. No damage mind you.
**Turrets count too! Really!** Allow kaiser to target his W on turrets, that way he's not completely screwed when he inevitably gets turret dived. If they're feelin generous, they could increase the size of the tower's W range.
**Undeadify minions!** Let him cast his W on a minion to turn it into an undead variation. Mordekaiser gets gold for the minions the undead kills, gives the minion a preference to attack champs, gains shield PERCENTAGE equal to mordekaiser's shield%. (Morde has 1000hp, minion has 400hp, at 10% generation the minion gets 40HP and the morde gets 100 etc)
**YOU SHALL NOT PASS!** Mordekaiser's metal wraps around his body, becoming an immovable, unpassable object that breaks projectiles similar to braum's shield. He gains a decaying shield = to his maximum iron shield. He can recast W to break the shield and immobility early. If you're gonna crap all over his mobility, make it for a reason, an awesome reason.
**Shrapnel bomb!** Mordekaiser can target the ground to create a whirling vortex of metal. It slowly builds up and after 4 seconds explodes in a range and damage = to the duration charged up. 33% damage to minions.