Ok. Mordekaiser is probably my favorite champion. He is tanky and hard to kill while his damage output is pretty good. This build is pretty versatile. From his core items you can switch into any style. However I find Tank style the most effective.

This build is best used for Pubstomps. It is viable in ranked games. However, it is more effective at the lower level, 1200-1400 ELO. It will carry you out of ELO hell, but I guess so will other tanky DPS characters like Jarvin.

Pros:
- Really Easy Champion
- Kills people easily
- Can hard carry
- Can actually do a lot of damage without damage items
Cons:
- Relatively Weak early game
- Needs to farm more to be fully effective
- Not really good at High ELO

The mastery tree you saw at the top can be varied. You could go 3/3 Deadliness 1/3 Archmage's Savvy OR 1/3 Deadliness 1/3 Archmage's Savvy . Its really personal preference there. The reason why I go 21/0/9 is because the runes help make Mordekaiser less squishy at level 1. Therefore I feel that I don't need to use my masteries in defence, and instead focus on offense. Some people might question using Perseverence Since it is only "half" effective, because it gives mana and health regen. I disagree since this build has a lot of health regen from Force of Nature and Warmog's Armor (if the game lasts that long)
So 4% increased hp regen, is quite a bit increased.

For Mordekaiser, early game is his weakest point because he is really squishy. So in order to fix that. We will deal with his squishyness with runes. Depending on the style you're going, you're reds will change. However I feel that this setup works best for me.

9x Greater Mark of DesolationGreater Mark of Desolation OR 9x Greater Mark of Insight
9x Greater Seal of Resilience
9x Greater Glyph of Warding
3x Greater Quintessence of Fortitude
Ok. Let me explain my reasoning for these runes. You would get Armor pen if you want a more hybrid-style tank. Or if you get Magic pen you would be more of an AP tank. Personally being a combination of both makes it harder for Mordekaiser to be countered (ie. Magic Resist would affect AP style more then hybrid style.)
I'm not sure if you've noticed before (You should if you have ever played mordekaiser before.) but his level 1 stats are ridiculously low. He starts out with 19 Armor 19!!!. When you're laning against someone who has armor pen and is ranged, it will be a living hell. By getting armor yellows You get 31 armor at level, Even if they have armor pen, At least you'll have some armor left over. Ok, luckily Mordekaiser's magic resist doesn't start as bad. He has 31 at lvl 1. After the runes you have 45 magic resist. Mordekaiser starts out with 501 hp at level 1. Luckily we're getting HP quints. Now. we have 578 HP. To put things into perspective I'll summarize the changes for you.

Base stats | Stats with runes
501 HP 579 HP
19 Armor 31 Armor
31 Magic Resist 45 Magic Resist

By getting these runes this allows us not to start with a Doran's shield, which leads us to...

Items, yes. Items make or break Mordekaiser. That is why it is imperative to farm well. However I will discuss farming later. You start off the game with + 1 . I'm not going to estimate when you should go back. Go back whenever, just farm well. When you port back, Unless you can outright buy a , you should purchase a and . The will help you get your other items faster while you're last hitting like a beast, and you can turn it into a later. Ok at this point your items should look somewhat like this:


If you have more money, continue building towards . Force of Nature allows you to spam more spells, because of the HP regen and it also allows you to chase (since Mordekaiser has no CCs, therefore making it hard for him to chase). You have two choices, you can either change your either into Or . You make the decision based on your team composition. If you're the main tank (Hope you're not) Then you should get Mercury's Treads, If your team has a tank already (best scenario), Then get Berserker's Greaves. You might be wondering why you get Berserker's Greaves, and say it is all **** for Mordekaiser, but just bare with me as I show you why I chose it.

This is going to be your core items.

This core allows you to auto attack and chase because of slow WHILE your spells are on cooldown, WHILE being tanky. Of course the later items are what really make you tanky. Although after your core is situational, I almost always build Tanky items as Mordekaiser isn't made to be the main burst, hes there to rape their squishies, because of his sustained DPS, because he is soo tanky.

Build example of a standard game:

This allows you to tank like a beast while putting out decent damage on their squishies. Usually the game does not last long enough to get the entire full build, as Mordekaiser is bringing the hurt on their squishy.

I always carry Ghost and Ignite, Ignite is pretty self-explanatory. Goes really well with your Ultimate. Ghost allows you to chase fast champions after team fights, and to buy time for your HP regen to kick in.

Mordekaiser is really good in a 1v1 lane, and is fairly good in a 1v2 lane. However depending on what champions are in the 1v1 or 1v2 lane, Mordekaiser may not be able to take them. So make sure you get a lane switch. I will explain specific match-ups later.

Farming with Mordekaiser is really easy, however, at lvl 1-3. You have to be very careful, If you spam your skills too much you will lose too much HP. However if you don't get enough shield, harass will hurt you. You will have to learn how to balance doing both.

Mordekaiser shouldn't harass till level until he hits level 3, His E does not do enough damage early on to justify hitting 1 champion for its cost and shield gain.

What makes Mordekaiser special, is his Ultimate. If you kill someone with Children of the Grave on them, they become your pet. You get 20% of there damage and AP, and some stats of yours are added to your pet. This makes Mordekaiser really really good in a team fight. As long as your team can focus someone down you can get a pet. Your team is supposed to focus down their carry. I usually prefer using Children of the Grave on the AD carries, as they hurt a lot and after the team fight you can use them to push towers, etc.
Using the pet is key, it allows Mordekaiser to fight 2 champions in a team fight, OR to focus 1 champion down to get another kill. It is very situational, and if you can learn to use it properly it will be very helpful for your team.

Mordekaiser's pet is very versatile. For example, After a team fight Mordekaiser has a pet. Mordekaiser can use this pet to tank the tower, and push really hard. Or it could be used to deal with an opposing champion in the form of zoning. What is really great about Mordekaiser is that with this spell he can change a 5v5 into a 6v4 (or 5v4 if 1 of your teammates died) since his pet does a lot of damage, and can take a lot also.

Mordekaiser's shield is another different aspect of Mordekaiser that can be abused. His shield will tank damage, so even if you have low HP. It will be beneficial to you to use a spell to get more shield. Because all damage has to go through your shield first, in order to take your HP. So if you get more shield, then it costs you HP (for the skill), then you will be in a situation where either then enemy thinks he can kill you but then can't because of your shield. Or where you would have died, but didn't because of that shield. For example, If you got ignited, and you will die if you just let ignite eat you up, OR use a spell (like your Q or E) on minions to gain a lot of shield that will tank the damage of ignite for you, letting you live.

Children of the Grave can also be used defensively. Since if you use it on a champion, it spell vamps and gives you their HP. It can help you live from a gank, incombination with ghost or the shield trick.

Though this tip isn't Mordekaiser specific. It is very beneficial to play the game using hotkeys. For using item effects like Randuin's Omen or when you level up WHILE in a battle, and you upgrade the spell that allows you to "kill your opponent or survive barely and it would not be possible if you didn't upgrade that spell" scenario, which has happened before quite often.
Play Video Sorry for no sound, I found out there wasn't any after recording them so :/

These are some teamfights from my recent games of Mordekaiser.
It shows me using some of the tips and tricks. Sorry that it is only a replay as I don't like recording while playing since I might get lag spikes. This fights were taking from my latest games as Mordekaiser.

Basically, as shown by the video. Mordekaiser tanks a lot with this build, and can initiate. However Mordekaiser shouldn't be the tank that keeps people of your carries. He is the beefy guy that walks into a teamfight and starts pounding their carry. If they focus you down, You die, but your team wins because you're very tanky and hard to kill, giving your team ample time to kill someone. If they kill your carry, it is the same thing, because it gives ample time for you to tank down their carry.

I'll give a rundown of who Mordekaiser is good against and who he sucks against in a lane.
Mordekaiser doesn't really lose in late game, unless you're playing against Jax.
This is theoretically if both players were equal in skill. If the Mordekaiser is more skilled than the opponent, the Matchups change. Same if the Mordekaiser is worse.
Green = People who are bad against Mordekaiser in a lane
Yellow = People where it is fairly even in a lane
Red = People mordekaiser sucks against in a lane
This is based on my experiences

Akali - early game, Mordekaiser will lose to Akali, however in team fights Mordekaiser, is not Akali's priority, and the fact that she is squishy and relies on Twilight Shroud, which Mordekaiser counters with his W and E.
Alistar - Mordekaiser early game is very susceptible to CC, and and the fact that Alistar can tank A LOT of damage, however again, Mordekaiser would probably not be focused in a teamfight, letting eat away at the enemy team.
Amumu - Mordekaiser can kill Amumu in a lane if it is a 1v1, but you should always be wary of his stuns, especially for a gank when he jungles.
Anivia - Mordekaiser can't really kill Anivia, because she has Crystallize, however if you do make it to Anivia. She will drop like a fly. Make sure to avoid stepping in her Glacial Storm which allows her to hit her Flash Frost really easily, which could potentially hurt in the laning phase.
Annie - Believe it or not, in a lane, Annie wrecks Mordekaiser, she will keep kiting him, so it will be hard to land your Siphon of Destruction. However once you get your it shouldn't be too hard to dispose of her.
Ashe - In a lane she will kite you all day, so try not to 1v1 against her at the low levels. However once you get your build going she is not a problem.
Blitzcrank - You might not be able to kill him, but Mordekaiser wrecks Blitzcrank in a lane, just be wary of his Rocket Grab, and he shouldn't be too much trouble.
Brand - Ahh Brand, he will hurt you, he is very annoying, but don't lose your cool. If you catch him offguard he will drop
Caitlyn - Caitlyn will kite you all day, Don't attempt to lane against her.
Cassiopeia - I have not faced many Cassiopeias, so I don't have enough information
Cho'Gath - It is fairly even, just watch out for his silence and knock up. Other than it shouldn't be a problem.
Corki - He has a lot longer range, and it is hard to harass
Dr. Mundo - Like you, his spells also cost hp. However since I run ignite always, laning vs him isn't really a problem.
Evelynn - Just Evelynn isn't hard, her stun is annoying but, in a 2v2 lane, if they focus you down early, it could get really messy.
Ezreal - Ezreal is really really annoying, his spells have low cooldown, and they hurt after a while, do not lane against him
Fiddlesticks - Hes pretty annoying with his silence and fear, but once you get to him hes as good as dead.
Galio - Galio can't really hurt you, but his slow is potentially dangerous in a 2v2. You will just outlast him in a lane usually. Hes hard to kill early on
Gangplank - Can be pretty annoying if he has crit runes. You will have to just soak up the damage with your shield and just keep laning
Garen - Pretty lame when you get silenced and have to eat his spin, but you should be able to survive vs him in a 1v1 lane, and in a 2v2 lane shouldn't be much of a problem depending on your partner.
Gragas - I have not faced many Gragases, so I don't have enough information
Heimerdinger - You're both great pushers, It comes down to his style, if hes focused more on Hextech Rockets It will be harder then if he focuses turrets.
Irelia - I have not faced many Irelias, so I don't have enough information
Janna - Her slow is annoying, thats about it
Jarvin IVJarvin IV - Watch out for his knock-up, hes pretty tanky, and has the ability to bring the hurt really fast. You should probably play more passively.
Jax - I have not faced many Jaxs, so I don't have enough information
Karma - I have not faced many Karmas, so I don't have enough information
Karthus - It is a toss up, usually it just comes down to if you can dodge his Lay Waste. Again you have to play passively, because Wall of Pain will not let you rush him
Kassadin - Pretty easy, just make sure you get your shield up before he hits you with your Q.
Katarina - Her harass with her knives, shouldn't be a problem if you have shield up. She probably will not Shunpo on to you. She is an unlikely opponent, but you'll have to play passive
Kayle - Can potentially hurt hard early game depending on his setup. If they don't have flat AP, then it shouldn't be much of a problem
Kennen - Shouldn't be too much of a problem seeing as his Q is fairly easy to dodge, just watch out for those stuns.
Kog'Maw - Don't get caught in his slow...Actually don't lane versus him at all.
Leblanc - I have not faced many Leblancs, so I don't have enough information
Lee sin - If he isn't jungling he shouldn't be too much of a problem,his dragon kick will be annoying cause he'll just kick you away.
Lux - If you get snared you'll take quite a bit of damage. If you don't, it'll be hard to get near her, so just last hit
Malphite - You can't really kill him, since he has a shield, but hes not really a threat to you. Watch out at level 1-3 where you can't get as much shield.
Malzahar - Hes pretty annoying, just be able to dodge his spells.
Maokai - Just dodge his Saplings as they hurt a lot. His other spells don't hurt as much. In a 2v2 just watch out being caught playing too aggressive, as his will probably snare you.
Master Yi - Hes pretty squishy, shouldn't be too problematic to deal with.
Miss Fortune - Really annoying if she opens with boots, then she will keep kiting you all day. Kinda hard to harass, but she doesn't hurt unless shes really trying to harass/kill you.
Mordekaiser - This will be a longer write-up as Mirror match-ups are always annoying for some. This match-up will determine whether or not you're Mordekaiser is better or not (obviously) It will also determine how good you are as a player in general. Mordekaiser vs Mordekaiser is a little bit tricky. Its tricky because, you're trying to strike the other where you will actually hit his HP. So not only are you trying to hit him, you have to hit as many creep as you can also, so when he Siphon of Destructions you, you will be able to tank more and deal damage. Because of this aspect, It can snowball really quickly, once you gain the advantage, and it will set the tone for the laning sequence.
Morgana - Just dodge her snare, and run away from her pool. Keep last hitting, she shouldn't be much of a problem either.
Nasus - Make sure you have shield, when he hits you with his Q. Shrug it off, and continue pounding him.
Nidalee - She should be hard to harass, and the same for her, Once she gets her cougar though, be wary if you still have just a Regrowth pendant.
Nocturne -I have not faced many Nocturnes, so I don't have enough information
Nunu - Nunu, if hes laning will be gay. Just try to last hit and not harass him, since he'll just heal it off.
Olaf - Olaf, if hes laning, shouldn't be much of a problem, just keep your distance and hit him with your E
Orianna - The good Oriannas I've played against will be able to harass you, and get last hits, while keeping distance away from you. Expect a challenge.
Pantheon - His spear throws, won't hurt you if you got shield, since hes melee he'll eat your spells, though watch out for his combo.
Poppy - Like Olaf, if she gets melee range, she will hurt a bit, so just keep your distance and use E. Don't stand near walls.
Rammus - Fairly easy, watch out for his roll and taunt in a 2v2 lane. Early levels (3-6), Your E will eat him. Just to harass him if hes in Defensive Ball Curl
Renekton - I have not faced many Renektons, so I don't have enough information
Rumble - Ahh Rumble, I probably hate this match up the most. He, like you, also has a cone shaped spell, and it will be a slugfest, however he will be able to zone you or kill you, as he has more HP then you and can kite you. :(
Ryze - Ryze can be annoying since his Q at early levels, will probably take out most of your shield, making you vulnerable during the duration of your downtime. And his snare makes it hard for you to chase him (obviously)
Shaco - You will eat shaco alive, with your Q and E, if he gets to close. It will be hard to do sustained damage on him so, harass him bit by bit, and finish him with Ignite.
Shen - Shen can do quite a bit of damage from his passive and Q, but it shouldn't be too bad, though he can tank quite a bit. Though his taunt might catch you out of position in a 2v2 or 1v2
Singed - Hmm, this guy shrugs off your early game damage like nothing. His poison will hurt and his fling will make it worse in a 2v2/1v1. If you're lit, he will be able to catch you if you don't have boots.
Sion - Actually quite annoying with his stun and shield combo. He is pretty dangerous.
Sivir - Her boomerang bounce is annoying at best, but with shield its not that bad. If you can catch her, shes as good as dead.
Sona - Pretty annoying, since her Q has pretty long range. It should be hard to kill her, so don't.
Soraka - Same as Sona, her silence and heals will be annoying. And her laning partner will most definitely be able to hurt you in that time.
Swain - If you get snared, Swain can pick at you even if you have had full shield early on. However you should have ignite so it can help you counter his ultimate.
Taric - Taric, like Sion and Soraka combined, can hurt you and he will be annoying. However the most annoying part will be the heal and not his damage, however I doubt he will be solo, so you should be play more defensively.
Teemo - He is like a pesky mosquito, he will pester you will poison and blind, but one misclick and your E will eat him.
Tristana - I don't like fighting tristana, she has quite a long range, making it easy to harass you and her E will cause you to take damage over time and reduce healing effects.
Trundle - I have not faced against a laning Trundle
Tryndamere - He should not be a problem till level 6, where he gets undying rage, and then its really annoying, but then you can just play defensively afterwards.
- I have not played against enough Twisted Fates so I don't have enough information.
Twitch - His cloak can be annoying but once you get your vision ward down, he should not be much of a problem at all.
Udyr - I have not faced against a laning Udyr.
Urgot - I have not played against enough Urgots so I don't have enough information.
Vayne - I have not played against enough Vaynes so I don't have enough information.
Veigar - Your shield will allow you to soak up his early game damage, unless he can instant stun, it shouldn't be a problem
VladamirVladamir - Laning against Vladamir will be easy at first, and it will slowly get harder, as his cooldown for his Q will be less and less. However if you play defensively, his Q shouldn't hit nearly as hard.
Warwick - I have not played against a laning warwick.
Xin zhao - His charge and knock up can be dangerous, however you also can pack a lot of damage, you should try to harass him, before you play aggressively, early on.
Zilean - His ult hard counters your ult, and his range on the time bombs, allows him to easily harass you. You should probably get a lane switch.

Note that, after getting a Force of Nature, the some match-ups are easier, or may give you an advantage

I hope you guys learned to to play this style of Mordekaiser, instead of just going AP. I would like to thank the viewers for reading this. I worked on this entirely by myself. Though my friends gave me some ideas in terms of some of the sections in the guide.

What I can say is: Have fun stomping noobs and getting out of ELO hell. :)