This build here makes a great tank and i usually have top damage or close to it at the end of the game. Mordekaiser can use this build anywhere on the map, but usually i stick to solo top lane and it is so hard to keep him pushed back.

The rune page i have is full of health regen just because i love it with my build, Force of nature and warmog's really keep me in fights and i hardly ever have to recall late game. Magic pen because you are AP, and then that little extra ability power per level helps late game as well.

My masteries are all in the deffense because this is a tank build, and a point in each other category for the summoner spells i choose.

I always start with dorans shield because of its extra health and health regen. I build my boots right after so i can move. Lately i have been building merc treds for magic resist since i am a tank but thats up to you.

Now depending upon the enemy team i go into force of nature or sunfire cap next. If i am really taking a ton of AP from the other team i will rush force of nature, but if its not to overwhelming i go ahead and build sunfire cap. Sunfire cap is my favorite item here, it gives me armor and a decent amount of health with giants belt, which is what i build first. Plus you can't beat the 35 magic damage per second to enemies around you!! That together with Morde's W move and you have so much damage coming off of you at one time. It's a must have item for Morde. If there are high damage AD champs agaisnt you, grab thornmail and then warmog's for that great health and stability in the game. Then the last item you get after selling your doran's shield will be an AP item of your choice, i like will of ancients for spell vamp, but i also would recomend Crystal Scepter, it gives you more health and AP.

Pretty basic here, you max your Cone move (E) before anything else, while getting your W move some points early.

I grab ignite for sure to go with your ULT because it's a devastating combo when an enemy champ is low health. I get exhaust just so i can slow down and get to the enemy or slow them for my team mates. Ghost or flash works well here too.