This build requires a very specific play style, It is a play style I have created and only works on Mordekaiser. For this to work you must incorporate elements of Human Engineering to be able to bait and trick your opponents into thinking you are weaker than you actually are. Pretty much every game I get reactions from the enemy team saying "wow" or "broken", and that is because of the 1 shot technique I created. Before attempting this build you must remember it is a very high risk build and I would only recommend to a MECHANICALLY GIFTED PLAYER. You DON'T need to be good at mordekaiser to make this build work.

Early Game
In the early game we are looking to bait people into trading with us. Unless you are against a ranged opponent it is practically impossible to loose trades with mordekaiser. It is imperative that you run up to them with your w and you heal off of them. Remember that your w heals significantly higher on jungle mobs and enemy champions. What you are looking to do is to poke them with your e to about 250 ish, you should be level 3 at this point, then you get two stacks of your q, activate w and then you flash on them and activate q and w then hit them with the e for the electrocute proc and ignite and you basically 1 shot them for like 300 damage at level 3. Throughout the early game you are looking to bait people onto jumping on you then turning it around with the insane damage and heal. It is all about the mind games
Mid Game
In the mid game you are looking to get as many dragons as possible so you can control them and you can take towers with ease. A higher level tactic which works better in higher elo would be to take teleport then get your jungler to ward drake when you hit level 6. You should be the first level 6 at this point as it will be super early in the game. Then you teleport, take drag with your jungler then you go round the back of bot lane and flank with the drake. It is practically impossible for the enemy bot lane to escape because they are level 4 or 5 and you have a 2.2k health drag which hits constant 200's to tank the tower and kill the bot lane. In Higher Elo's this can decide the game.
Just remember that without flash you are severely under powered as you cant flash 1 shot their adc or their mid.
Late Game
By the time you hit near full build you can easily hit over 2k with the 1 shot combo we talked about. At this point your main objective is saving flash for their adc, you need to set up your 1 shot then flash on them, activate ult on their adc and 1 shot. The beauty of this is that no matter how fed their adc is you will always be able to 1 shot ( as long as they dont have GA). The more fed their adc is the better as you basically become a god as you heal from their fed adc and you can literally 1v5 the enemy team with their fed adc on your ult. The last tip would be the elder dragon. Similar to having a fed adc on your ult the elder dragon turns you into thanos as your health is massively increased and you have a massive dragon with tons of hp which hits constant 400's by your side.

I will make a video soon showcasing what this play style looks like in game.
Just remember it is the mechanics and the mind games which you must master before you are worthy to wield the infinity gauntlet.

Domination - Electrocute, taste of blood, eyeball collection, ravenous hunter
Sorcery - Scorch, Absolute Focus

Take w then e then q. Max w then q then e and r whenever possible. Remember that q must be maxed second the that 1 shot potential and the w first for the healing. W is only good for getting health down during laning phase for setting up 1 shot and getting shield to tank harass.

Pros
Can one shot people from half health at level 3. Can also 1 shot from full health at level 6 with gunblade
no one expects the damage
the more fed their adc gets the stronger your team gets cuz your gonna 1 shot them later and use them to kill their own team
tons of friend requests and compliments from both teams because of how amazing you are
Cons
Ranged people are aids
Garen
Mundo
Vlad
No flash means no 1 shot which severely puts down your play potential
If you suck then you will severely put yourself behind as this build never changes no matter who you are against. Go big or go home