Here me out on this one. AP items seem to be a bit too strong right now and are quite a bit stronger than their AD counterparts, the most egregious of the lot being Void Staff and Hourglass.
Like how come Void Staff gives more penetration, more damage, and is cheaper than Lord Dominik's Regards? It makes no sense to me at all. Like how come that item is allowed to give 5% more penetration and 25 more damage but also have the bonus of being 150 gold cheaper than the AD version?
Hourglass is the AP item that counters AD champions and Maw of Malmortius is the AD counter to AP champions but Hourglass is way better than Hourglass. The only thing Maw has over Hourglass is that it gives 5 more MR than Hourglass gives armor. Hourglass is not only 350 gold cheaper than Maw but it also has better build components and gives more damage than Maw does even when Maw has Lifeline triggered. They provide damage negating actives, Maw with Lifeline and Hourglass with Stasis but Stasis is a way better active. Going back to build components Fiendish Codex gives 10 more damage and is 200 gold cheaper than Caulfield's Warhammer while also giving 10% CDR just like Warhammer. Seeker's Armguard when fully stacked up gives 15 more damage and 10 more armour than Hexdrinker while also being 200 gold cheaper, though Hexdrinker has the better active. Lastly Stopwatch is just Hourglass active but 600 gold and one time use and it still reduces the cost of Hourglass once used. So in the end Hourglass has a way smaller finishing cost than Maw along with a better active, better components, better stats overall, and is far cheaper.
So yeah, the gap between AD and AP items, especially in the penetration and defensive category is rather obvious and either Void Staff and Hourglass should be nerfed or Lord Dominik's Regards and Maw of Malmortius should be buffed.