ok so the first think i feel i have to get out there is that Morganas Black Sheild is a SPELL sheild. it does not block physical damage only magic damage and disables. so if these someone fighting an auto attack character your spell sheild cant help them.
i have proven time and time again that Morgana is a character that should be helpful to your team. ive only lost 1 ranked game that i played her in and that was only my second ranked game and i wasnt ready to play ranked. ive gone 8-0-14 in a ranked match with her only having a dorans ring a cata and boots of speed(this was a low elo match mind you) but she is a character who can stay in a fight even when she is low. her built in spell vamp is enough to keep her alive in most situations. just dont play stupid and you'll do fine

each item in this build has a skill that it goes with and a reason to get it in that order, and damage isnt. Rod of Ages-survivability and sustanability, Rabadon's Deathcap-good ap early so you have a large sheild, Zhonya's Hourglass-the prock doesnt break the your ulti but you need to get in front of them and thats why i use flash, the Void Staff is simply for damage, and the Banshee's Veil is so that you have a sheild on yourself so you can use your spell sheild on others such as your carry or healer

after putting my first point into Soul Shackles what skills i put points in depends on who im laning agains, how often im being ganked aswell as by who, and weither or not my lane parter can keep himself alive. but i always max my Tormented Shadow first because if im being hit hard or ganked often and i can always put it under the creep wave and heal as im being chased

i only put Flash twice not because im an idiot or that i did it on accident but the way i play morgana its really the only spell i need
the spells that a recomend on her are, excluding Flash

Clarity - when i use this spell I never have to return to base. I can throw out my Tormented Shadow when i get low on health and heal and with clarity i can keep a constant mana suply

Ghost - it is a useful skill for getting away when a teamfight is going bad or keeping up with the enemy when they are trying to get away from your ulti

Ignite - Its good when someone is very low and you arent sure where the enemy team is

Teleport - Morgana is great for ganks and to help push lanes. the faster she can get to another lane the better

when using Morganas ultimate, Soul Shackles, in team fights what i do is i will use the ulti prock my Black Shield on myself and before they break threw my sheild i will my Flash to get in front of them,so that they have to either continue running toward me and get stunned or run back into my team, then prock your Zhonya's Hourglass so they can't kill you so before they get stunned. i usually follow this up with my Tormented Shadow and Dark Binding so that i get atleast 1 of the kills at this point your team should be there to finish them off

the only person who should leave a teamfight after morgana is the tank. what i usually do is sheild him befor i leave so that either he can use it to last longer everyone else gets away or he can use it to get out aswell. if we dont have a true tank or our tank died in the fight then you sheild the carry and snare the person the other team who has the most cc, and and if it comes down to someone needing to die to get the team out it and you dont have a tank, or you have a fail tank who is so worried about his k/d/a that he will leave teamfights early, then it should be you to die to get your team out