Can Kog'Maw ever get his AP ratio back on E?
Kog'Maw could be a niche artillery mage back in the day, he had some good wave-clear with his E to get through laning phase. Although he had no mobility or hard CC whatsoever, his long ult range let him have presence in fights later in the game.
However, his E was nerfed back in 2016 for the sake of making ADC Kog stronger. They whacked a whopping 20% AP ratio off of it as well as some base damage, making it so it was completely unfeasible for him to survive laning phase.
Switch back to today, where Kog'Maws immobility and lack of CC, as well as the lack of any prevalent tanks in the meta make him a less popular ADC than Kalista. In fact, his highest winrate is when he forgoes levelling E at all until level 13, only putting points into QWR. With Rageblade being his core item now, I think it would be okay to put his the 20% AP ratio back on his E.