This Morgana build is for those of you who want to stay on lane and never leave due to mana or hp problems. She has a lot of magic resist and armor plus the spell vamp to keep her hp up. With these items I found it easy enough to maintain enough mana to farm through the entire early game without going to base very often. After the laning phase is over you need to get blue buff as many times as possible to maximize your potential.

Glyphs - Flat Magic resist
Seals - Flat Armor
Marks - Magic Penetration
Quints - Movement Speed

Mercury Treads - I like them over Sorcerer's because the slight power you lose without the additional magic penetration you cover up with less deaths due to CC and magic damage (often early 1v1 mid lane is quite magical)

Spirit Visage - I really take this item only for fun. It is a great way to make your spell vamp even more effective while at the same time making you harder to kill by your enemy AP champs. You might want to change this into Force of Nature after you have finished your build.

Rod of Ages - Really a great item to get for any Morgana. It is your only mana item so it is essential you get this early enough so you don't have to rely on those blue buffs all the time. Also makes you that much harder to kill and a Morgana without hp is a much more viable target for the enemy assassins than a Morgana with a huge hp bar.

Hextech Revolver/Will of the Ancients - Again another item that makes you more durable with the extra spell vamp and more effective damage-wise with the additional AP.

Zhonya's Hourglass - A must have especially against heavy AD teams. Makes you more effective and harder to kill. Flash + Ulti + Hourglass into the middle of the fight can tip the scales of any team battle even in the end game.

Rabaddon's Deathcap & Void Staff - For extra damage when closing in the end of the game. If you manage to get all these items in 45 minutes, you have done very well with your farming and team fighting.

Flash for easy escaping during laning for you will probably push a little being Morgana. Also for entering combat ulti blazing in the team fighting phase.

Teleport is excellent for pushing, defending and ganking. I wouldn't leave home without it if I'm playing Morgana.

Pros - This build makes you very hard to kill and you can stay on lane virtually until the end of time (even easier with a steady supply of blue buffs). You gain your lost hp back very quickly from wraiths or wolves or enemy minions. You can take more punishment than a regular AP Morgana and it makes it easier for you to take hard hitting enemies 1v1. Also gives you more precious seconds in end game team fights to cast all your spells the way you want to.

Cons - You do less burst damage. It takes time to get really effective, but before that you will have to farm hard (which is still easy enough) and actively take part in ganks and team fights during early game.