By geting so many mana runes, you can easy stay in your line for a long time, and get as much as posible xp, and gold, also geting some magic penetration make your spels more efective.

in masterys i am chousing 9-0-21, for geting the magic penetration in the offencive part, and geting mana regrain, cooldown, movment speed, and XP bonus, also couse to give flash a point, to make it have less cooldown, so it are ready, when it are needed

I go mid with morgana, from lvl 3 (or 1) you have your sheld ready, that take of 100 magic damage in lvl 1, normaly its magic damage that are delted mid, with champs like karthus, vlad, morgana, ryze, kog, and so on, so if you are good to use your sheld, you can take of 100 damage, werry often, that make you to be able to stay in the line much longer, and while the other champ take all the damage you delt, you can loose less life, and get more xp then the other one

the items i chouse, is almoust like thous from another morgana buid, an ye, much here are the same, but i want to make some smal changes, so i have made my own
bying dorans ring, give you mana regrain, 5 pr. 5 sek, pluss 3 from mastarys and from runes (4.5 i think it was) is 12.5 pr. sec, together with morganas passive (Spel wanp) you can farm creeps, and restore life at the same time
afther that i buy boots for the penetraion, alows you to deal more damage, without have to buy AP, i normaly have enouf G to buy soulstealer at the same time, then you start gank, normaly (avaranged ranked game enemies let you get 5-10 stacks right a way if you are good to aim with Q, and a team that help you when you gank

from here i go rabandons, abyssial scepter and the hourglass, whatever you need the moust, you go first

rabandons 30%, and 155 AP is the best item in the game afther my opinion. then the hourglas give 100. And with the 20 less resist on nerby enemies chaps, the abyasal scepter is a good item, also you get some magic resist and armor, but you normaly do not need it

In a team fight, you are both the suport and magic carrie (or, i am), shilding somone how need it, or the strongest meele dps love to team with champs like AD sion, nocturne, xin and jax, morgana + one of them is REALY fun to play, shild him to reduse damage, and just let him get feeded like hell, deal as much damage as possible, but save your ulti up for larger groop of champs, or if your teammate need some more help, then just that you hit 30-40% of max hp with your snare (if the enemie dont got magic ressist or hp items)

PROS:
great farmer
one of the best ultis in the game
one of the best pasives in the game
stun slow and "sneare"
one of the best nukers
REALY good in teamfight

cons:
cant play all alone, you are not the best AP carrie if you dont got a team that help you, (or you help), need a bit of teamplay

the best, or one of the best part with morgana, is how long she can stay mid without have to recal, and with clearety you can stey there forever, the other spell i chouse is flash, the best spels of them all, use it to flee, if you get ganked, or catshing (a) runing enemie(s), also you, in a teamfight, you can flash into the enemies, use your ulti, and then the active of the hourglas, then afther the ourglas active are out, they alm oust instently get stund, and you can get out of there, your teammates come, or you can K.O of some of the enemies