Hi everyone.I'd like to start out by saying i've played mordekaiser for more than one year now,it is my favorite champion since i was lvl20(Or earlier,i can't remember for sure).When i started playing him i remember i used to follow exactly the recommended Items,and they're not that bad,i actually did well.After some time i found a great guide in this website(Unforgiven's guide) that helped me a lot.After a few months however i developed my own playstyle based on Streams i watched and games against other mordekaisers,this play-style is focused on being a good source of Magic damage,with decent lane sustain(great with Hextech Revolver),and,nice survivability.I'm not a competitive high elo player however i do have a lot of experience with mordekaiser and i guarantee you will find useful information here.

9x Spell penetration reds
These are mandatory for early game damage.Lategame they don't help that much but for squishies that don't get much MR they're still useful.
9x HP Regen/lvl Yellows
I assume if you're picking mordekaiser you are going top lane or middle(in some rare circunstances),you will need the regeneration so you can spam your abilities on your enemies(not on their minions,more on this later).
Flat CDR Glyphs
These may not make sense to you right now,but,along with the CDR Masteries you will have a large increase in your Magic DPS specially in team fights,wich leads to more Health regained through spell vamp and makes you tankier.For a long time i used Flat Magic Resist,Magic Resist/lvl and Spell Penetration,and CDR is what i had more success with.
Spell Vamp Quints
Since their release i've been using them and even though they're not really useful early game,when you have at least 100AP and a Hextech Revolver you start "feeling" that they're helping,and when its lategame they can actually help you.Feel free to swap them for Movement Speed,because it is possible that it is actually the best choice.I'm not entirely sure on the spell vamp quints.

There is not much to argue here.except for the Spellvamp.It is good to have if you have the spellvamp runes,even without them its somewhat useful.other than that standard Mana-less caster masteries.Buff duration not needed for you because you're leaving blue for your Main AP Carry and Red for your Ranged AD or Jungler if your AD doesn't need it.

Ignite:
It is a must on mordekaiser so you can deal a lot of damage with your ult combo and ensure no one escapes because of that silly Health Potion on their inventory.
Could be swapped for Teleport if facing a tough lane.(Rumble comes to my mind)

Ghost:
I take ghost over flash,because it gives much more utility in team fights than flash and allows you to stick like glue on running targets and catch up to them.you can get Flash if you feel like it but i dislike flash on mordekaiser.i run flash on everything else but Olaf.

Start with Doran's Shield.
Why?

With HP Regen/lvl and Spell vamp Runes/Masteries you will have good sustain by lvl4.
120HP To survive more burst
Armor to tank Minion damage and your lane enemy/jungler.Both usually are AD.

Other Options:Boots and 4 Health Potions.(Wait 10 seconds after minion spawn for 4th Potion,you will get there before any of your minions are killed. if you can't wait 3 Potions are fine.)
I Don't recommend starting with Amplifying Tome because 20AP isn't that much and the lack of sustain can make your laning hard.If you think you can do it get it and buy Hextech Revolver ASAP.

When you go back to fountain you will want to Buy Boots and a Hextech Revolver,if possible Sorcerer's Shoes.When you go back to lane with this you're pretty much back to the Immovable object state that made mordekaiser get nerfed months ago.

You have some Options now.
You can buy Hextech Gunblade for More damage on Mace of Spades and a ranged disable,with more spellvamp and lifesteal,OR you can get Rylai's Crystal Scepter for a slow on ALL your abilities,slightly more ability damage,less Mace of Spades damage,and Tons of Health.

If you need more HP to survive Burst Get Rylai's.If your team lacks reliable CC get rylai's.
If you're having trouble Bursting down your victims get Gunblade,if your enemies don't deal much damage to you get Gunblade. if you really need a ranged disable that has a higher range than your Syphon of destruction get Gunblade.
I usually go for rylai's because of the tankiness it gives.But thats my preference you should get what you feel fits best with your playstyle.You can get Sheen anywhere in this mess if you Want the extra burst.I don't find it necessary because it delays you by 1260 Gold on your other items,but it is good damage on your Mace of Spades,i do it sometimes.

After you Buy one of them buy the other,its absolutely needed.

Well,now that you have your 2 first Big items the game starts heading to lategame and so you do.Now you have several ways to go.

Classic Tanky mordekaiser
This one is most useful if your team already has a lot of damage and needs you to soak more damage while still dealing some.
Now you get Chain Vest and Negatron Cloak,in wich order you decide based on who deals more damage on the enemy team.
Good items to get:

Force of Nature - Movement speed,a lot of HP Regen and Magic Resist.a must for strong AP.
Sunfire Aegis - Good HP,Good Armor,and more AoE damage.
Guardian Angel - If it's nearing the end of the game.
Abyssal Mask - More Damage,More Magic Resist,and helps your AP Carry.Great item.
Thornmail - Only if it is really necessary.not a big fan of this.
Zhonya's Hourglass - Great active,you can burn your Cooldowns,let them destroy your shield,activate this,and burn your cooldowns again without taking any damage.Also a lot of AP and good armor.



Bursty AP build
This is one is something i used to do 6 months ago,it is still viable but not the best choice IMO.
You get Rabadon's Deathcap, Void Staff, Zhonya's Hourglass.Your Mace of Spades won't hit as hard as it would with the Lich Bane Build,but your ultimate will be devastating.I'll elaborate more on this in the gameplay section.

Cookie Cutter Lich Bane Build
This one is great for Dealing and Taking damage,has a incredible amount of Burst(specially on 1v1) and you're reliable on lategame teamfights because you have Guardian Angel(More on that later).You get Rabadon's Deathcap,a Chain Vest if AD is hitting Hard(You may need it before Deathcap), Lich Bane,When lategame comes you turn that Chain Vest into Guardian Angel.

What about Will of the Ancients

?
It is not worth it in my eyes. it is good early game,yes.But it only has small amount of extra spellvamp compared to the Gunblade and provides no utility apart from being an Aura item when you compare it to Gunblade's ranged nuke+Slow.You could get it but i find gunblade to be more useful lategame specially with the AD for a higher damage with mace of spades.

Laning:

You can lane Mid or Top.Never go bottom.You're not a support and you're not an AD carry.
Laning top:
You will be facing some kind of bruiser with good sustain here,most of them are AD.You should stay passive until lvl5 or 6,focus on last hitting.Do not push your lane.if you wish to harrass you will wait for one of those situations:

Enemy can't retaliate for any reason
You will get a full shield from the damage you did,resulting in his retaliation being useless.
He is coming for a last hit and you're safe among many Minions.

I usually only harrass if i want to get a kill by lvl6 with Ult+Ignite,otherwise focus on farming.

Last hitting:
You should use your auto attacks to last hit,if it isn't possible try to hit as few minions as possible with Siphon of Destruction and last hit with it.With enough practice you can hit only one minion most of the time without even "aiming" for more than half a second.Use Mace of Spades to last hit if theres a single minion left,it will heal you by a decent amount with spell vamp.

Cool Tricks
Always buy a ward when you go back.2 is even better.this is by far the coolest trick ever.
If you fear a jungle gank and must stay hidden you can use Creeping Death to last hit.Send it on melee minion at the right time and it will kill nearby minions without exposing you too much.It can also be used to harrass someone without putting you in danger.it will keep them away from your minions during that small duration so you can either damage them if they go for last hits or deny them some gold.
When you're level 6,and you got Ignite and ultimate ready you can trick your oponent into fighting you if you're sure you can win by doing this:
>Harrass him
>Pretend to be afraid,back down a little
>Do this until he chases you
>When Siphon of Destruction is ready again use everything on him.
>He should be dead by now.
*Important only use your full combo if your enemy is 65% Health or lower*
*If you're 50% Health or lower don't try this.i recommend at least 70%*

Mid game(Also known as:Sh*t starts to happen)

Dragon control and turrets should be on your mind all the time now.If your enemy left the lane to roam,push other lanes,teamfight and you can't help your team against him fast enough punish him and take his turret.However by now you should be already roaming with your team.Clear jungle camps when you're passing through.
You're a great pusher by now,if you think there's no risk of a team fight,go to someplace warded(By you or your team) and push it as much as you can safely.

Lategame:

Stay with your team.You're a beast at teamfighting and a valuable asset to your team.Maintain baron control.Be ready for team fights.

Team fights:

This is where you shine.You should communicate with your team before engaging on who to focus and who you wish to ult to acquire a ghost that will gently destroy your enemies for you.

Ultimate strategy in team fights:

Generally you will want to ult their Ranged AD carry,because it usually is the weaker champion that deals most damage on the enemy team.getting to him is a hard task however.How do you kill him them?

>Hextech Gunblade active on him
>Run in his general direction,use Creeping Death on yourself
> Siphon of Destruction hitting him and as many enemies as Possible
> Mace of Spades on his face
> Children of the Grave and Ignite

Then you should run out because you will be the focus of everyone,after all this damage their carry has either to back out or become your trigger happy slave because he will be extremely low.If any of your team mates tried to help you and kill him he will be dead.Re-engage with other targets when your abilities are UP( Mace of Spades/ Siphon of Destruction)

You can also target the enemy AP Carry,your ghost is not only useful for Auto attacking your enemies!it will give you a % of his AP and AD.Lategame you can reach huge amounts of AP if you kill an AP carry,wich is sometimes good for dealing more damage with your other skills if you can't kill the AD carry or if that annoying Ahri is wrecking your team and you need her dead ASAP.

Always try to hit your abilities on as many enemies you can to regain Health and Generate shield.Don't chase their carry and abandon your team,get back into the fight.If you're low you can ghost and run away,regenerate your health on minions and run back to the fight.If your ranged AD is in risk of dying and you can save him do so.he is more valuable than you in most cases.

Cool tricks
If you have Guardian Angel are going down,try to take someone with your ult.You will be able to control your Ghost while reviving,and your enemies can't target you.When you revive use the rest of your combo to get more shield and finish anyone who is left.you can Possibly engage in 1v2s with this strategy and end up winning.

Timing your Lich Bane proc:
If your Lich Bane proc is used when you're hitting Mace of Spades all the damage will be Magical!That means you can deal a ****load of magic damage to someone if you time it correctly.always try to do that.

Using Creeping Death + Rylai's Crystal Scepter to save someone:
With rylai's your Creeping Death will apply a slow,if someone is being chased and you can't interfere for some reason use it on them,they will have extra armor and MR,deal some damage to the enemy chasing them if he gets close enough,and,whenever he gets close he will be slowed,aiding on the escape.

I'd like to thank all my clan mates that helped me develop my play style,specially my friend Morgado that won't read this anyway(lol).I'd also like to thank those that play Mordekaiser at high elo and stream it allowing me to understand how it works in higher level games.I'd also like to thank TheUn4givenRage for writing a great mordekaiser guide here,wich i think you should also read to get a different view on the subject!
Thanks for reading,Sorry for Grammar mistakes and any typo!