I used to wonder how Morgana could take half my hp with one spell combo. Now I know and you will too. The thing is.. I went through the top morgana guides here and no one is using offensive masteries, some dudes are using cd glyphs ffs.. so I thought trolollolwtf?! ..these clowns need too take a look at a pro guide :D

Morgana is considered a support champion because of her shield. For the shield to be of some value, you have to put a point in it pretty early. Also, if the shield breaks after a single stun from an enemy its not gonna be as awesome as a shield that can block two stuns, right? Correct. So if you are laning against two stunners I'd recommend to get up to three points in the shield before you max Dark Binding. One point before Soul Shackles, and two right after. If you put your shield on an ally after the enemy stuns her, you fail. If you can't clear the bushes of Caitlyn's traps or Teemo's mushrooms, you fail. Your job is to control the lane, that involves taking aggro from minions and spell vamping them so that pantheon can step in someone's face while taking reduced damage because he's shielded. And when they try to retaliate you torment the ground under them and bind their ***es to it. As a side note to taking minions' aggro: do not be afraid to tank large minion waves once you get a couple of points in Tormented Shadow.

You do not want to spam morgana's spells. They cost too much. As a rule of thumb in early game: Tormented Shadow should only be used when you can hit at least 6 minions with it. And never ever fire dark binding unless you will hit the enemy. Because missing means putting yourself in a vulnerable position. Also, since the passive of Tormented Shadow is reduced magic resistance you will ideally want to hit the enemy with Dark Binding after you put Tormented Shadow under them. This might seem very difficult, and it is. However, keep in mind that it is actually possible to cast Tormented Shadow after dark binding, and still reduce the enemy's magic resistance before Dark Binding hits them. This involves leading your enemy, a good feel of your range and the velocity of Dark Binding. Try to remember as well, that all melee fighters will want to get close to you, or blinkers such as Akali or Xin Zhao. Let them. Put a Tormented Shadow under your self as they charge in, wait 2 seconds and fire dark binding. That way, they will take the full duration of Tormented Shadow and catch a very painful snare.

The shield is very important. You want it to absorb as much damage as possible. They only way to do that is to have a lot of ability power. Hence only AP/level runes. The runes I recommend will give you a whopping 5 ability power per level. If you can, save your spells till you hit level 3.
You don't need magic penetration because you have it from Tormented Shadow. You don't need mana runes because you will have two doran's rings and 10 mana/5 by level 5 and not 12 mana/5 at level 18 like you would with Greater Seal of Scaling Mana Regeneration.
You don't need the whole utility tree because you will have more cooldown reduction with Ionian Boots of Lucidity than you would with Intelligence .
Awareness is a waste because it should be next to impossible to force morgana to recall and lose xp, if it happens you just get back with Ghost or Teleport.
Quickness might be of some value, but thinking it is necessary is a mistake and reveals that you don't know how to use morgana's spells. Keep the enemy at range with your spells.
Meditation is ok but you don't even need mana or any of your spells to kill the first couple of minion waves with the offensive masteries that I recommend. This is even more true if you have a lane partner. Besides, having just a bit more damage, attack speed and armor penetration, will ensure that the enemy falls after you ult them. They will not get away with 50 hp and you will not need Ignite to finish them off. Good luck killing someone with 3 mana per 5 seconds when all your **** is on cooldown.

Many morgana players take flash. It might be kinda cool to flash in between 3 enemies and ult them. But mostly I see people use flash to escape or to land a snare. You can do the same thing with ghost. Just think about it for a moment: You're in a tight spot and you snare whoever is chasing you then flash away. Which will get you farthest from them do you think by the time the snare wares off, flash or ghost? And to land a snare: Ghost will enable you to get so close to them that they can not dodge the snare and not a single surprise shot as you would have with flash. Ghost is also more useful when you are trying to land your ultimate. I have successfully stunned people with it even after they flash because the slow effect of it keeps them from running away while I'm ghosting after the poor suckers.

The stuff above works great in every game. The only thing to consider is the order in which you get them. Take Zhonya's Hourglass before rabadon's cap if they have a fed Karthus (or amumu+kennen) or a lot of AD. Take Void Staff before Lich Bane if they have a lot of magic resistance. Take Lich Bane before Zhonya's Hourglass if your team cant push turrets or if the enemies have a lot of movement speed. Don't take Banshee's Veil instead of Rod of Ages, learn to use your shield instead.