Alright, Kog'Maw. Let's do this.
W: Bio-Arcane Barrage Current: Doubles attack speed and attack speed cap. Attacks deal 55% AD and apply on-hits normally. deals 1.25% max HP per 100 AD and .75% max HP per 100 AP on-hit. Halves cast time on abilities.
Current PBE changes: AD ratio removed, deals 2% max health on-hit base.
My change idea. Builds up to double damage (110% AD + normal on-hits + 2.5% per 100 AD + 1.5% per 100 AP) based on his normal attack speed. So if you had 1 attack per second, his W would double that to 2 so you can just hammer away at someone with on-hits if you want, but if you only attack once per second while his W is on, it would deal an actual auto attack worth of damage instead of horribly nerfing it.