Think this will get Sivir disabled?
https://www.youtube.com/watch?v=BAppXaD2Dk8
Support Morgana is my main. I tend to play her as a roamer.
Masteries:
I always take 21 Utility (+starting gold). The rest is either Defense or Offense (CDR, Expose Weakness).
Runes:
Bog standard AP page but with some mana regen blues.
Skills:
Open with WQE, then R>Q>E>W
Items:
Open: Spellthief, 1 Ward, 2 Pots, Yellow Trinket. I try to get Sightstone, 1 Pink and a few pots on my first back. I always place my pink on the river entrances near blue/red (not the patch of grass on the river).
Core: Sightstone, Mobility Boots, Spellthief
Situational: FQC, Aegis, Crucible, Randuin, Frozen Heart are my usual other pickups. I only pickup Zhonya if I'm getting fed, or if they have means to blow me up while I ult. FQC is VERY useful for me. It makes it much easier to setup a Q. If I don't have any particular item I need to build, it's my go-to after Sightstone/Mobi. I haven't tried the reworked Mejai yet.
Playstyle:
Laning: I only use W when I have 2-3 stacks on Spellthief, otherwise I go OOM. I try to target the one with less sustain. Avoid hitting minions especially casters.
During 6: Walk and ult, then hit them with Q as soon as the stun wears off. Works very consistently until mid Plat. I always try to use it as soon as the cooldown wears off.
Teamfights: Don't feel bad about shielding yourself to ult. I use my ult as either an engage or peel.
Matchups:
I hate Tristana, Corki, Draven. Cait and Kog somewhat.
I really hate Janna, Lulu and Sona. Braum makes it harder to pull off kills when you hit 6 because it's harder to wear them down.