This is my first guide. my spelling isnt great, neither is my grammar. its a nerd guide, not a spelling bee.

Morde has no ability that will disable or properly initiate. The reason people think hes a tank is because his passive is a "shield". Don't think of it as a shield, but an extra health pool with extreme regeneration. The best part, is that your health shield will mitigate dmg based off your armor/mag res!! What does this mean??
It means a morde who stacks health is out of his F@$king mind. His health shield is technically an infinite source of health, why would you need more?
It means that your chainmail will affect how much dmg your health shield takes.
It means when your build is done, you'll be healing yourself faster then they can damage you.

my core build is: Boots of lucidity, spirit visage, will of ancients.
For a balanced team, i will generally get my core + Zhonya's Hourglass and Abyssal staff.
The extra ap with the armor/mag resist make your shield MUCH harder to take down.

As a side note, Zhonya's Hourglass's active is great! Imagine: your over confidant and took on the team of 5 all by yourself. You probably have time to kill 2 of them but now your about to die. Ult, creeping death and Zhonya's active and YOUR BACK TO FULL LIFE FULL SHIELD! finnish off the rest of the team.

Depending on the the opposing team make up, or if im dominating or not, i might add a Mejia's, or a Thornmail if they have several carries, Abyssal + FoN for all AP teams. If your Dominating and the game isn't over, Death Cap.

Some people say that a FoN is wasted if you arn't stacking health. While its true its health regen will be diminished, it by no means useless! Most of the Champion abilities are magical and 70 mag resist will always be helpful. The health regen will be big enough to always cover your spell cost and the movement bonus is just great.
Boots of lucidity will help spam your spells along with Spirit visage giving you 33CDR in total. A SURPRISING boost to damage, which in turn means more health and health shield for you.
Mejia's is always a toss up. If you get one, but cant keep more then 4-6 stacks, sell it ASAP and move on to hextech revolver.
Hextech Revolver is great. An AP boost and spell vamp. that means not only do your abilities hit harder and charge your health shield faster, it also heals your regular life bar as well!
This gives your a total of 33% CDR, 25% spellvamp, substantial AP and some mag res.

If Yi and Ashe and MF are getting you down get a thornmail. It will be the last time they try to kill you, i promise. the Mitigation it provides is amazing! 100 armor will reduce their effectiveness to a de-clawed cat, who will end up hurting themselves while you stay at full health. This tide-changing item is often overlooked. If AutoAttackers are hurting you, Hurt them back.
Same idea with the Abyssal Scepter and Hourglass. For a balanced team both those should give you enough mitigation to stay at full health unless chain-stunned and 5v1 focused.

You'll ALWAYS want a solo lane. Your a GREAT champ for a 2v1. If no lane is available take mid. Your Priority Is R > E > W > Q

Max out Siphoning Of Destruction ASAP. I will put 1 point in Mace of spades at lvl 2 *IF* i feel comfortable with pushing the lane fast and hard or if im forced to tower hug.
The reason is that its cooldown is lower then creeping death, so you can spam more often = more dmg, and more shield. *IF* Im getting harassed by ranged (Cait) ill get a point at lvl 2 in Creeping Death and use it to shield the TANK MINION or the second melee minion (making sure it has full health) when it enters the minion fray to build up the shield a little, but to harass the bad guys as well.
Whether i put a point in Creeping, or Mace, i ALWAYS max Creeping Death second. Its synergy is soo damn great! Armor, Mag resist, and an AOE DPS that charges your shield! YES PLS!

If your engaging enemies, be sure to have some opposing minions near you to re-charge your health.

If your running away from a fight with low hp, spamming your abilities MIGHT just save your life! if your running by a wave of creeps, a lvl 5 siphon will give you a HUGE boost in health!

With this build you cover almost every facet of a good champion build. The only thing missing is CC and an escape ability. But the whole concept behind a Mordekaiser is to be very aggressive. The wonderful thing about a Morde is that more often then not, in ranked games, your the LAST one to be focused in team fights! People always go for the squishy carries, who *dish out the most damage*. They know Morde has no CC abilities, so dismiss him as useless soak. Trust me, they will be shocked when you out-DPS your carries while out-healing their incoming damage. By level 18 your ult will be dealing ridiculous damage, not to mention healing you for a crazy amount as well.

Be wary: Stuns/Silence means the death of you. Your survivability is based off spamming your skills non-stop. If you are stopped from spamming, you are stopped from living. A good counter to a stun/silence heavy team is a quicksilver sash.

As previously mentioned, Morde is EXTREMELY susceptible to Stuns/Silence/Suppression. Please note, i did not put snares as you can still use your abilities if snared.
A remotely well played Kassadin will screw Morde EVERY time. His silence can out-range your abilities placing you in a no-win situation, CHANGE LANE immediately. I can't stress this enough, Change lane! Kass will eat you every time 1v1.
A great Zone of control-er like Cassieopia will make your life hard, if she's well played. If you can't get close to kill minions, your are a useless Morde.
Malzahar's Ult will mess almost anyone up. If your laning against one, I would rush a Quicksilver ASAP and shut him down all game long.
Any melee champ is easy to Zone with Morde. Even Ashe or MF will take a defensive stance when faced with your farming.
Any well-played stun/silence champ can be a problem for you, so be careful.

I would specify, at the beginning of champ selection that MORDE IS NOT A TANK. when you select morde ppl assume hes a tank and they wont choose one. Be aware most people do not understand what a tank is and will argue, que-dodge and be generally unpleasant.

Dont flame till you try it, and please leave only constructive comments, there's no need to be mean.