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.
Other info :
You can use other item for morgana, or other order, depending on the consequences, I think you can off-tank, if you have many AD versus you, you can take Frozen Heart, ect...
And my skill build is inappropriate for all, you can custom it if you want.
So, for gameplay, you have to play for know how to play morgana, I can't help you on this point.
Good luck !