Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
i played Morgana for more than 400 times and i'm trying to optimize my build.
Then main idea consisting with this build is to give morgana more preload dmg (preload means --> max dmg at one point, for solofight or at the begining of a teamfight, to get the firstkill in 5vs5)
Then main item in this build is "Deathfire Grasp". With this itembuild "Deathfire Grasp" does 50,92% of the current enemie hp instant dmg (every 60 sec.). With this build you get 3495 mana with lvl 18 and maxed achrangel's. Furthermore this big manapool give a ap boni to the archangel's staff.