In this build, you are going AP tank, and also trying to protect yourself from hard hitters, while keeping great survivability. This build will more than likely keep you alive for long periods of time, and serve you well in team fights especially.

With the major ability power, spell penetration, and health runes, it makes for a deadly early game combo. Not only will these runes destroy the other team early on, it makes for a great harass with the spell pen and ability power. The health runes also make for better survivability and keep your health rising consistently throughout the game.

Starting off with doran's shield is probably one of the best items you can start off with morde, for the sole fact that it provides you not only with health, but also health regen which is a key when playing morde. The next two items, sunfire and force of nautre are meant for mid game, and will give u great survivability and help to counter any fed AD or AP players, providing you with armor and magic resist. The next item, rylai's crystal scepter, will provide you with more health again, while giving you more AP to harass, and get those much needed kills at this point in the game. I also like the fact that it gives you a slow, so morde now has some CC, instead of absolutely nothing. Zhonya's hour glass is also a great itme against heavy AD champs because of the fact it provides you with more armor, and also provides you with more AP, which makes morde even more deadly with his abilities. Thornmain I like if your playing teams heavily based upon AD champs, like tryndamere, master yi, or warwick. This almost gurantees you that you protect yourself from these hard hitters.

The two summoner spell I really like for this build is ignite and ghost. These two work out great, especially when either trying to kill someone, or trying to run away from someone. With ignite it works really well if they are at about half health (depending on the champion). When they reach that specific targeted health level, all you do is ignite them, and put your ult (children's of the grave) on them, and almost guarantees if you cannot reach them while they run, that ignite and your ult will definitely kill them. Ghost can be really key especially early game when laning and you are dieing, and dieing fast. This can help you to escape those sticky situations.