All of you who think he is OP, please take time and read this.

Morde's main role is meant to be a tank. So, what is a tank?

In RPG-s, word tank determines a player with high survivability which draws attention of boss/enemy players while his teammates who lack survivability but have damage potential do their roles.

How does tank draw attention? Against AI controlled bosses he generates large amounts of 'aggro', which makes him a priority target. However, human players know this and know that priority is eliminating DPS characters. So, tank needs a way to make enemies to attack him.

Most tanks have some form of CC which helps them to draw attention:

Rammus, Shen - Taunt
Amumu - Stun, Snare
Garen - Silence
Maokai - Slow, Knockup, Snare
Taric - Stun
...

Mordekaiser doesn't have CC. So, he needs above-average damage for drawing attention. You know that he can and will punish you if you ignore him, so you have to take him out.
Imagine if he had low damage. He would be ignored in teamfights, and ignored tank is useless.

Now, let's take a look at his shield. It is not OP, as most tanks have a trait that boosts their survivability.

Sion, Shen - Damage Shield
Amumu - Physical damage reduction
Rammus - Armor/MR buff, damage return
Taric - Heal, Mana Return, Armor Aura
Singed - Health Boost, CC reduction
Garen - HP Regen, Slow Reduction, Damage reduction
...

Compared to these, Morde's shield is not that strong.

Of course, Morde can neglect tank role and go AP. There is a simple solution to this.
Just kill him. For that damage he has traded lots of survivability and will go down pretty fast.

Thank you for taking time to read this.

+1 to you. I've never played Morde, so I can't say from personal experience, but I know when playing against him, he's either ignorable or super squishy. Either way, it's pretty easy to deal with him, as long as you don't fight him IN THE MIDDLE OF YOU MINION WAVE so he can get easy shield.

I don't quite get what you're saying...he's not a tank? So, he's balanced? You also don't have to go full AP and neglect your durability, and there are some items that work well for Morde to simultaneously improve his offence and defence. That's pretty much the optimal way to play Mordekaiser. He can be overpowered (which I do not think he is), but saying "he's not a tank" (which he definitely isn't) doesn't prove he isn't overpowered.

You are wrong, Morde is not a tank, Morde is a carry. He generates large amounts of threat (mainly with his ult) and forces the enemy team to focus him.

Edit: This should clarify my point, skip to the last pard for Morde. http://www.leagueoflegends.com/board...d.php?t=237576

Morde is balanced by having no CC, no chasing or escaping, and a very poor late-game.

Problem? Too bad. Lrn2play.

Morde is not a tank.

Ergo, stop worrying about how he compares to tanks.