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.
So, I'm going to start out this build summary by giving major props to Flood for making Morgana Prime as it is the build I started with to win me many a game when I was first learning the terrifying beast that is a full fledged Morgana. I also think that it's high time a fresh build based on more current items and recent updates come into existence. This guide is my first attempt here at Moba to create a character guide and I thought it best to pick the character I am best with.
I've seen a lot of builds focusing on force for AP on Morgana and that is all well and good, and I even tried to keep the majority of force in this build, AP is sexy and don't we all know it. But I was looking over Marks and realized that the magic pen was largest here ( beyond quints but the force there is too good, perhaps switching one quint for magic pen, I admit I haven't tried that yet.)
So the other Runes have remained Force whilst all 9 of the marks are magic pen to give you that extra boost in damage early game as everyone has some form of magic res. early game, and for added magic pen late game for your void staff.
I will roll about here and make a second character sheet for Morgana in a while that focuses on her more non-solo item build ( as you do indeed want to go rod of ages first if you aren't mid) but until then I'll explain all the items from the mid perspective. I go for the amplifying tome first for the extra boost to AP in the very beginning and not to mention that it is part of your build for Mejai's soul stealer ( the item you will be getting next as soon as you have the money and the enemy pushed back enough to get it.)
With soul stealer you should have enough AP to really be pushing against who your laned against and possibly getting that early game kill, the second you have enough you should get your sorcerer's shoes and a brilliance potion if you have the money (extra AP is nice). Now you should be going about trying to gank the other two lanes when your mid is clear to build up soul engorgement and getting the pieces of your rod of the ages, rod of th ages is a nice round stat pump that keeps giving you additional stats and in only ten minutes after purchase it gives quite a fat sum a nice boost to AP and also health for more survivability.
Next item is Rabadon's death cap for the massive AP boost then void staff for much needed magic pen as the enemy team will be building magic resist by this point. It comes here that I'm unsure whether deathfire grasp or Another rabadon's is the better choice. Honestly it depends on personal preference and how the match is going and if that tank is just too hard to kill with your own nukes.
I'll be putting more here later, tips and such for the build, much more in depth look on the whole play style as well. I just wanted to get the idea's out here so that I could get some general reviews and flesh it out more later on.