Not Updated For Current Season
This Mordekaiser build is a tragedy for all enemy teams.
Start off with a Regrowth Pendant. This will allow you to stick around for a very long time. Ideally you should solo lane, but if the opportunity is not there, be more patient and possibly recall sooner to buy an extra health item. This will allow you to adapt a more aggressive playing style to make up for lost time. It's case to abuse your E skill against enemy minions as much as possible and for the final blow you follow with your Q skill. Both abilities deal damage to multiple targets at once and the amount of damage will ensure most gold will enter your collection. Continue this routine until you get your Warmog's Armor equiped, quickly followed by your Sorcerer's Shoes.
After you have upgraded to Warmog's Armor and got your boots, you will gain a nice amount of health and health regen over time. This will give you that edge over other players to be considered a tank already. Now it is time for you to analyze your opponent. Do they have a lot of mages, get your magic resist up first by buying Force of Nature. Start off with Negraton Cloak for your magic resistance and then finish the rest. In case your enemy is mostly containing fighters, you should get a Thornmail instead for obvious counter measures. For a balanced team it is case to determine whether it's important for you to be the strong tank or take part in dealing the damage. I prefer to play it more safely and start of with Force of Nature and then get Thornmail. The magic damage from your Thornmail is nice ofcourse, but if you can't stay alive during your teamfight, it's rather pointless.
Now it's time to not just look tough during teamfights, but act the part. Buy your Shurelya's Reverie for some extra health, health regen and the cooldown reduction. This will allow you to constantly spam your abilities into the enemies face. For the final blow you can get a Nashor's Tooth for added attack speed and more cooldown reduction or you can get a Rylai's Scepter to deal additional damage per attack. Any enemy team allowing you to get to this phase are now considered suckers.... you will call the shots!
Have fun and give me your feedback!