Morgana is my all time favorite champion. Played right she can be very hard to kill and can harass very well. When she is ready to commence with the melting of faces she can turn the tide of many team battles. Often her deaths are the lowest and assists are the highest.

This build has only one purpose. To melt faces. To that end items, masteries and runes are selected primarily based on their AP, magic penetration, or cooldown reduction. Sometimes +mana regen is selected. Any other stat generally comes along for the ride because the item has a good AP/GOLD ratio.

I always shoot for best end game. Morgana is usually level 18 before anybody else (unless you have feeders on your team, in which case that sucks for you). Thus Per Level runes are usually the best bet. Magic Penetration though just doesn't have a good alternative than Flat Runes.

9 x Greater Mark of Magic Penetration: Flat +Magic Penetration, just about the only good choice available for this build. Can substitute 9 x Greater Mark of Scaling Ability Power if you really want to.

9 x Greater Seal of Scaling Mana Regeneration: Per Level +Magic Regen, can't really go wrong with mana regen to keep you casting. The +AP per level runes are lackluster at best.

9 x Greater Glyph of Scaling Cooldown Reduction: Per Level +Cooldown.

You have two choices for the Quintessences. Either go for more cooldown or more mana regen.

If you are finding yourself constantly oom and thus useless to your teammates go with:

3 x Greater Quintessence of Scaling Mana Regeneration

If you seems to be fine with mana then go for:

3 x Greater Quintessence of Scaling Cooldown Reduction

Masteries revolve around AP, magic penetration, cooldown reduction, or whatever is the best choice to get to the next tier. Insight and Spatial Accuracy are selected to help with your Summoner Spells.

If you bursting with too much mana late game you might wish to swap Meditation for Awareness , maybe even drop Insight into Awareness too.

First let me talk a little about other builds. Lots of builds have people buying Doran's Ring first because its very efficient for its stats, some even suggest buying two. However, it has some key disadvantages that I find ultimately do not really help. The primary disadvantage is that it does not build into a better item. You will have to sell it for a loss. The second is that ultimately 100 health is not all that worth it. If you want a bigger cushion in the early game buy a health potion, you'll save some gold. Third, 15 AP is not enough. Even two rings will not be enough to make Tormented Shadow at level 3 kill a wave of creeps most of the time. You will still need level 4. By then you will quickly be buying much better +AP items.

The items are simple:

Sorcerer's Shoes: +20 magic penetration along with movement is key.

Will of the Ancients: One of the cheapest end pieces with high AP/GOLD ratios. The +spell vamp is a good bonus.

Mejai's Soulstealer: The second highest AP/GOLD ratio item, Rabadon's Deathcap being the highest. Getting it early to build up your stacks is the key to this item.

Archangel's Staff: On its own it can provide 87 AP. (45+(1400*0.03=42))=87. If you add to that your base mana it starts to rival most other items in AP/GOLD. Also adds much needed mana regen.

Rabadon's Deathcap: 155 AP right off the bat is nothing to scoff at, +30% AP power makes it the best damned +AP item period.

Hopefully the pattern is apparent to you. All these items provide good base AP but also add additional AP based on other stats (or AP).

The final item is kinda up to you. I choose Zhonya's Hourglass most of the time. It has lower than average AP/GOLD ratio however, it allows you to lay the smackdown with your ULT and maybe even survive long enough for the end burst. Great for team battles.

A good purchase order is as follows:

> > > > > > > > > >

Meki Pendant for that early mana regen.
Sorcerer's Shoes on first recall.
Tear of the Goddess to start stacking up +mana and Hextech Revolver on second recall unless you already have enough to buy Will of the Ancients outright.
Finish off Will of the Ancients and buy Mejai's Soulstealer on third recall.
Try to buy Archangel's Staff on fourth recall to upgrade Tear of the Goddess.
From there finish off building the Archangel's Staff and start building up for Rabadon's Deathcap by getting a Blasting Wand or Needlessly Large Rod, whichever one you can afford.
If you are going for Zhonya's Hourglass as your sixth item choose either Chain Vest or Needlessly Large Rod depending on your situation.

First lets talk about Soul Siphon. At first this doesn't help you. In the low levels you aren't dealing high enough damage and it starts at a low 15% spell vamp. However, once you get Tormented Shadow to level 4 and high enough AP you can just about heal half your life with just one cast on a wave of creeps. With Will of the Ancients and sufficient level you will top out at 55% spell vamp.

Dark Binding (Q): Whether you use it to aid in escaping or use it to stun an enemy for your allies to beat them down, it is a very useful ability. Often builds have you get this first instead of Tormented Shadow. You will need to judge for yourself. I find most of the time Tormented Shadow does a better job of harassing the enemy due to creeps almost always being in the way. Learning how to aim is key for this ability, learn to judge when to shoot in front of the path an enemy is going or when the enemy may turn back.

Tormented Shadow (W): This is both your primary farming ability and your harassment ability. In mid to late game it is also how you heal yourself after during battle. W>Q is a key combo that can cost your enemy half their life and heal you to full. Get this to level 3-4 asap to get the kill on the back row of creeps. If the cluster of creeps is close enough together you can manage to kill all six. Be conservative though, a miss-placed pool can end up hitting less creeps instead of more.

Black Shield (E): This is your second escape ability. I don't use this for stopping damage often. Rather I use it to prevent other status effects, like stun/silence/slow. Veigar can be the bane of many champions existence, but this ability will allow you to pass right through his Event Horizon effect. I grab it early game, but don't touch it until the last 5 levels. Most likely a melee will be the one to kill you and this ability has no effect on their attack damage.

Soul Shackles (R): Your Ult. It's slow effect can be great, but the primary use is its burst damage. 350 damage now and 350 damage 4 seconds later would be good combo, but really the added AP is what does the trick and this AP build makes your ult pack a serious punch. With 550 AP you can deal up to 1800 to enemy champions near you (and heal you for 990).

W>Q>W>E>W>R>W>Q>W>Q -> R>Q>Q>E>E>R>E>E

I get Teleport because Morgana is one of the slowest movers in the game, thus anything that can help lane jump in emergencies is good.

The second summoner spell to get depends on your play style.

If you are having to go back to home base often and potions aren't cutting it, then Clarity can help alot.

If you are having difficulty positioning your ult without getting spam killed before firing it off and/or you want an escape mechanism Flash is good.

Alternatives

Ignite for that extra face melting and bonus 50% reduction in healing.

Ghost if flash just isn't for you but you want some better maneuverability.

Flash. I mention this again because in some cases if you usually use another summoner spell but are seeing a large number of games with Jarvan IV or some other champion that has an ability you can't normally escape from then you will want to choose this summoner spell.

I farm hard early game. The items in this build are expensive costing a total of 14190 gold for the full build. In order to get anywhere near this you either need to farm lots of creeps or MDK some champs. Your level 3 (with sufficient AP) or level 4 Tormented Shadow can kill a wave of creeps netting you all the gold. A good target is usually the back 3 caster creeps.

Unfortunately I find I don't get many champ kills till late game. You may rack up the assists well enough, but you will not usually be fed kills. Being too aggressive will usually make you a feeder instead.

I also like to harass quite a bit. Using Tormented Shadow to both get the last hit and take some health off a champ early game can be a good way to force a champ off the lane for healing back at home base or if the enemy champ is careless enough you can swoop in for a Dark Binding hit or your ult to get a kill. Always be on the lookout for a clean Dark Binding hit. If you can manage a kill without dieing, using the W>Q>R combo can kill many enemy champs in the early game.

Mid game you may find yourself switching lanes quite a bit because of forced team battles. A good strategy can be to lay down your pool to kill a swath of creeps while you use Teleport to join up for a team battle.

Mid game team battles are much the same as end game team battles, except that you may be able to step into the middle of them to use your ult Soul Shackles earlier than is advisable for end game team battles.

At the end game, for team battles your Dark Binding is a key spell. Especially when you are either fleeing a battle gone wrong or to shut down an enemy champ so your team can lay the smack down. Use your Tormented Shadow judiciously but often. Psychologically enemy champs almost always scatter to get away from the pool, it has the added bonus of healing you with your 55% spell vamp (assuming you have Will of the Ancients and are high enough level) and can help whittle down health.

Timing your ult Soul Shackles is something you will have to learn with experience. For single or double kills the W>Q>R combo can usually take down at least one champ. Sometimes you can even get a double kill if the enemy is stupid enough and you are smart enough. For team battles you want to wait before stepping into the middle, especially after the enemy has focused on your tank or someone other than you. If you have Zhonya's Hourglass you may be able to risk stepping in earlier. Most likely though, you will die after firing off your ult if they don't die first. So hang back, throw a Dark Binding or two and use Tormented Shadow to herd the cats and shave off more health, then use your ult to finish things off.