It's my first guide i'm posting, and i'll accept any advice at all. Now the build guide:

As you may know, not everyone likes morgana, they think she is not cool at all, weak, useless..
Well, let me tell you something, morgana could be one of the most important players of the team. She can kill,save and assistamazingly easy!

There are some basics you should know about her:

First, I had been using morgana for a long time now, I used another build "morgana prime by flood" but now i'm using my own which i think it's more complete.

1- Morgana has a very important issue, COOLDOWNS. The best way to make them short is to buy glacial shroud, and then buying frozen heart
2- Morgana doesn't need much skill, but you'll need perfect timng and of course good aiming! For this I can only tell you "practice"
3- It's crucial to start in the mid lane. If you do so, you'll be gaining a lot of gold which is required to get the items used for morgana.

It's very imoprtant to know what the skills are able to do before playing morgana

1-Dark Binding: an ability that snares the enemy at some distance, morgana throws some kind of energy ball that deals heavy damage and snares the opponent
2-Tormented Soil: this ability creates a circular poisonous soils that only inflicts damage when an enemy or minion stands on it
3-Black Shield: an ability extremely important, I mean, it stops EVERYTHING, it will shield you and prevent any kind of negative status
4-Soul Shackles: morgana's ultimate ability, she creates a powerfull ray between her and the enemy's, can attackmore than one enemy player, and it will slow and take down life for s little period of time, then it will stun the enemy dealing heavy damage

5-Soul Siphon: Morgana gains 15-35% Spell Vamp, meaning that it will recieve healt when damaging with magic

When mid laning you are defenitely going to find another ranged player, it could be something great, beacause you could be a real pain in the *** for some of them.

Easy mid enemies: akali, ashe, cassiopeia, karthus, tristana, lux, janna, sivir, miss fortune, veigar, teemo, twisted fat
medium difficult mid enemies: ezreal, zilenean, katarina
hard mid enemies: caitlyn, malzahar, vladimir, leblanc, heimerdinger, vladimir

when starting the game in mid lane just try to avoid the enemy from earning money, use your tormented soil so as to force him to stand back, if he doesn't get closer as if you were going to attack him, he will scare and pull back, if he doesnt, use ignite and pull back, you will deal heavy damage to him just beacues he is on its first levels!
as youare going to earn a lot of money and probably won't be with low hp beacuse of morgana's passive you can stay on the line without any problem until you reac 2000 gold, so you could go back and buy tear of the goddess and sorcerer's shoes, and if you have any money left, it could be really important for you to buy elixir of brilliance (250 gold)
use your tormented soil to kill the last row of minions andfarm lots ofgold (in level 3 tormentes soil kills them with no help at all)

at this point of the game you'll be around level 10. If you did an amazing job the rest of te player should be at around.. level 7-8 so you could gank top or bot, whoever needs help!
I recommend to help whenever your mid enemy is death or had to run away to the base beacuse of low healt.
When ganking the best idea is to wait in the bushes so when they comeclose you start with the ultimate and then stun and blow them away.
when ganking soulshackles>dark binding> tormented soil> ignite
but if you are on a regular fight:

black shield>tormented soil>dark binding>soul shackles>ignite(if necessary)
you should get rabadon deathcap now

after getting rabadon's deathcap you will be dealing lots of damage, you are going to be like the best partner ever, never hang in there alone, because morgana is not a tank, she is squeashy!
hang in with the group,and assist them by binding, whenever you are running away try to shield the last one of your partners who is running away to avoid stun,snares, or even some ultimates!
by the end of the game you should get a very positive score with a max of 4 deaths
once you have void staff, you might be able to kill everyone, nomatter who it is

for the record, with this build, my best score was
22/3/21

remember, morgana can be the most important character if you know how to use it!
the most important part of this build, is the use of elixirs, and practice!

everytime you go back buy elixir of brilliance, it will do an inmense difference than if you don't buy it!

1-doran's ring(475g) at the beggining of the game
2-sorcerer's shoes(1100g) + tear of the goddess, first time you will be going back
3- archangel staff (1860g)
4- Glacial Shroud (1525g)
5- Rabadon's deathcap (3600g)it's escential for killing, it could be baught by separate because it's quite expensive
6- Void Staff (2295g)
7- Frozen Heart (1250g)

You can do some changes, something you can do is to avodi buying frozen heart, by buying mejai soulstealer (cheaper), but it's quite hard to get to 20 stacks though. also you can change it fot morello's evil tome, but there isn't much of adifference with frozen heart, so I recommend frozen heart, but both options are viable!