Im new at making guides, so they may not be perfect in any way. but im doing my best to share with you, how i prefer to play some of my favourite champs.

This is my guide to a nice strong and fairly tough Mordekaiser.
Combining lots of ability power, a bit of damage, and some good resistances and hp.

You can use any rune setup you want. sometimes i go with tanky runes if there are a lot of weak champs on the team, but usually i use the setup i have here above. some magic pen, and loads of AP. Gives me the AP to do great early game damage while i build up my Force of Nature.

Masteries can be chosen like runes, as you prefer. mostly i use a setup like displayed above. but again sometimes i use more tanky setup, depending on my team.

I always open up with Regrowth Pendant and a Health Potion. then i go for Boots and another Regrowth Pendant. I finish my Force of Nature as fast as possible, this will compensate for the hp cost on your abilities and the slow base movement. Now i go for Ionian Boots of Lucidity and a Rylai's Crystal Scepter. Mordekaiser have no cc of any kind, so the slow from Rylai's Crystal Scepter is a very nice compensation. Now i build either Zhonya's Hourglass or Hextech Gunblade, depending on if i need armor or more damage. And yes i know mordekaiser dont benefit that much from damage, but the damage in Hextech Gunblade gives quite a nice boost to Mace of Spades and its well worth it with AP and spell vamp. After these 2 items i finish up my build with whatever i like. mostly its a Rabadon's Deathcap. but sometimes i take situational items like Thornmail for a fed AD carry ect.

Summoner spells are all up to your own personal preferences. i usually take Flash and Ignite/ Exhaust. but Ghost/ Teleport are also nice choises. Take what you like and kick butt ^^

Pros:
Good damage
good survivability
nice minion farming
A Ghost pet
A big freaking mace! :)

Cons:
No real CC
Slow base movement
His mace is not big enough ;)

That was it i think. Feel free to comment and vote :)