The current overview of AP items does not allow very big item diversity in the build paths. It also does not provide AP Bruisers or AP Assassins adequate build paths without heavily favoring Mages.
AP Items do not allow a build path that sustains any diversity. Most AP champions build Luden’s Echo, and fill out the end of the build with Rabadon’s Deathcap and Void Staff. That is 3 items that nearly every mage is building each game.
AP Bruisers do not have adequate build paths to sustain the playstyle. Any AP items that give resistances benefit Mages as much as Bruisers and Mages are still building the AP Items that give health.
AP Assassins are building the same items as AP mages with nearly no change in build path.
There are quite a few AP items with problems, but I am only going to talk about 3 of them, as they are the heaviest offenders of the problems.
1. Luden's Echo:
With Deathfire Grasp being removed, Luden's echo was giving some of the burst back to Assassins, while less burst.. it provided waveclear and MS. Currently, Luden’s echo builds out of Lost chapter which is very problematic. This means that mages will rush Luden’s echo, giving mages even more waveclear than they already had putting Mid lane Assassins at a disadvantage, taking away from roam opportunities. Removing the movement speed on the item hurt Assassins a lot.
Proposed fixes: Switching Luden's Echo with Spellbinder, making Spellbinder the Mana/CDR Item with Lost Chapter and getting old Luden's back.
There may be other ways to fix this problem, but that is the point of this discussion.
2. Banshees Veil:
Banshees does not offer AP Bruisers enough defensive stats, while giving too much offense. it really only is benefiting mages currently. When do you see a Galio, Sylas, Mordekaiser, or any other AP Bruiser-like champion going Banshees? You don't. You see it being built on champions like Syndra, Ahri, and others.
Proposed fixes: Add health to the item build path and remove CDR.
Once again, there are probably other ways to fix this item but this is just a quick thought.
This item in the past, and still is overloaded. It offers flat pen, (which ad champions had reworked to lethality because of how strong flat pen was) grevious wounds, health, and ability power.
Proposed fixes: Remove grevious wounds, create a new item similar to AD Carry build paths where there is a 2nd Void staff but with less pen and grevious wounds added.
I think a lot of players would support a change like this.
That all being said, there are more problems with AP items that exist but I wanted to go over some things that come to mind while playing Mid lane.