As a huge fan of Mordekaiser, I have found that, even though playing a more dps focus on him is fun, tanking with him is more effective and can deal much more long term damage. Leaving an empty slot for your own item, you can pick whatever item you want, but with this build, you should be able to stand toe-to-toe with, and this isn't over exaggeration, all 5 of the enemy champions and get at least 2 kills, if not scare them to run away. As a bit of bragging, there was a game when I was being "ganked" in my enemies' red buff by 4 champions, one support, two AP dps, and a melee dps. To their surprise, I would kill one of them with my ultimate and go on to kill another before the other two champions run, leaving me to finish red buff and return to base. Follow this build, and play Mordekaiser right, and you could repeat this story.

Getting the magic penetration runes for Mordekaiser works extremely well throughout the game, giving you an advantage early game as well as keeping your damage from dropping later game. Being that your items will mostly be tanking items, you will need another way of getting damage and this does it.

Armor runes early game is amazing because you basically start with a free Cloth Armor, meaning minions will do less damage, as well as champion auto attacks. A thought you want to keep in mind through this guide is that your resistance carries onto your shield, which means, the harder to get through your shield, the harder it is to kill you.

Cooldown runes are a great way of keeping moves off cooldown to keep the dps up and protect yourself. Getting per level runes or flat amount runes can be used depending your opinion on their effectiveness, but more reduction means your ultimate has a less cooldown, which means more life steal for you, as well a nice pet to help you slaughter the opposing team.

Movement speed quintessences are an overall great thing to buy because you can never have too much movement speed. Whether it is for catching up to prey fleeing for their lives or running for your own, these will help you accomplish both. Also, since Mordekaiser doesn't have any form of CC to speak of (until you get the Rylai's Crystal Scepter) that movement speed will help you get those early game kills that would otherwise elude your grasp.

Going down the Utility tree is a personal preference because you get that movement boost, more cooldown in both champion moves and summoner spells, etc. However, since you are building a tanky build, and wish to go down the Defense tree, that works just as well. You do, however, want to always get the 9 points in the Offensive tree because of that magic penetration and cooldown reduction.

Before I go on to giving you a list of items to get, there is a purposely open slot so anyone who uses this build to get whatever item you think this build may need

Starting off with the Regrowth Pendantover the Doran's Shieldis a personal gauge of whether a Mordekaiser is a veteran as this champion or another noob trying to join in on the raping parties that Mordekaiser mains throw every game. This is because Doran's items in general are more beginner items in the fact that they can't build into anything, only give minuscule stats that other items can give more of, and getting an item that builds into a core item is, in general, better. In Mordekaiser's case, the Regrowth Pendant offers more health regeneration, which is crucial when your skills are being casted at the cost of your health. While the Doran's Shield gives armor, which would help against minions, the Regrowth Pendant is an item that builds into an absolute must for Mordekaiser, the Force of Nature. Getting the Force of Nature is so crucial because the health regeneration given from it is ridiculous, and will allow you to lane forever. The benefits will only pile on once you get more health and keep regenerating it while your shield absorbs most of the damage. It also offers a great movement speed boost, which, as I explained earlier, is a great thing to have on Mordekaiser, especially before he gets his Rylai's Crystal Scepter. On your first time back, you should continue building your way up to the Force of Nature, but you should spare some gold for your Boots of Speed.

Once you have the Force of Nature, you can decide to either get the Thornmailbefore or after the Rylai's Crystal Scepter depending on the opposing team composition. Four AP champions and one AD champions begs the need for the Rylai's more than the Thornmail. Regardless, you will want these items next before continuing on into the build. As a side note, for those who may not get why Mordekaiser NEEDS a Rylai's Crystal Scepter, Mordekaiser lacks any kind of CC of his own, and until he has this item, depends on teammates in order to get kills. Once he has this item, it makes all of his skills slow anything they hit. Since all of his skills are aoe, with the exception being his ultimate, Mordekaiser becomes a great initiator because he can slow the opposing champions, allowing your dps to catch up and lay down the hurt. It also gives him incredible chasing power because his ultimate has an enormous range, allowing him to throw it on prey that will be slowed for 10 seconds!!! This is not taking into account that you will be hitting the poor champion with your other spells, slowing him/her even longer.

Warmog'sis the icing on the cake, the item that basically seals the enemies' defeat simply because it will be next to impossible for them to score an ace. Plus, combined with the Force of Nature's ability, the Warmog's Armor gives a crazy amount of health regeneration, meaning you will almost forget the last time you hit the back button for reasons other than to just buy something. Also, getting the stats maxed out on Warmog's will take next to no time for Mordekaiser because he has some of the best farming capabilities in the game (because of all of his AOE).

At this point in the game, you should be noticing the amount of time it takes for the enemy to drop your health. See you emerge from the shadow of war should more than enough to make them run for their dear lives. Just remember, you don't even have a full build yet. This means you can either take advantage of your tankiness and get some AP for more damage, get more tanking items to lower their hope even more, or get some spell vamp to make sure you just never leave the team fight. This empty space should allow this build to go on to last even a Tryndamere and a Kennen ultimate at the same time. So have fun with choosing your next item, because all it means is that you will most likely being carrying the game even more.

Getting Siphon of Destruction first is by far the smartest choice for Mordekaiser because it does the most consistent damage out of all of his moves. It also is what makes him such a nuisance to lane against. Siphon of Destruction is also the best at charging up your shield, since it hits an indefinite number of targets and has an ability that gives you bonus shield based on how many targets are hit. Leveling up this skill makes the damage scary early to mid game and will be by far the main reason why the enemy champions stay out of experience range.
Creeping Death is a great skill for Mordekaiser because it gives him damage while being effected by CC, as well as make him even more tanky. Leveling this up as a 3rd priority, your ultimate being 1st and Siphon of Destruction the 2nd, helps tremendously in making you a much harder target to kill, since, if you have enemy minions around, it will constantly be giving you a shield, as well as make that shield harder to take down with the added resistances. As another great effect, Creeping Death creates a permanent slow for those caught within it once you have the Rylai's. This move can literally mark a "creeping death" for those who get caught in it
Mace of Spades is a great farming skill because it resets your auto attack, meaning last hitting minions becomes a breeze. However, this move doesn't really give you any help in the terms of tankability. Getting one stack in this skill is more than enough for a great deal of time as another source of dps.
Children of the Grave is a skill that basically makes you impossible to kill. At half health, grabbing a pet from a 3v1 gank can turn around and give you 2 kills, if used right. First off, you want to grab this skill at every opportunity, obviously. As a great tip, using it on a squishy target is much more preferred than a tanky one. Remember that whomever you mark must become the focus of all your skills, because once you gain its ghost, you become next to impossible to kill. Also try to use this skill only when you are sure you can kill its target, because otherwise, you just get some health back, and you might as well have used it on a tank.

Getting Flash is a great choice for Mordekaiser because it can usually close enough distance to get in a killing blow via Siphon of Destruction, Ignite, or Children of the Grave. Having a defensive nature to it, you can also use Flash as a getaway spell, using it like you would with other champions.

Ignite just about guarantees a kill if comboed with Children of the Grave. During the laning phase, getting a champion at half health is a good time to use these two, if you can commit to getting in the rest of your moves. If you want that absolute guarantee of a kill I mentioned earlier, a quarter-health champion can get dropped with the minimal effort of Siphon of Destruction, then chaining Ignite and Children of the Grave. In general, Ignite is an almost OP summoner spell for Mordekaiser.

Farming with Mordekaiser isn't even a challenge. With 3 AOE spells, clearing creep waves is almost too fast for laning. In a 2v2 lane, Mordekaiser can easily out farm both champions in a 1v1 lane. This is a great trait for him because this means he is not bound to getting kills to get his items. Let the game go long enough, and even a shut down Mordekaiser early game can come back to become a monster later game (had plenty of games that were the case).

Mordekaiser, no matter how you build him, will get kills, I can guarantee that much. However, going tanky will get kills, no deaths, loads of assists, and you will just laugh at feeble attempts to gank you as you just walk away with hardly a scratch. This build has never let me down and I hope you can reap the benefits from it as I have.