Champions like Vayne and Master Yi are supposed to have true damage to really be able to tank bust and add further damage to their ability to kill targets overall. And as a tank main, I'm okay with this, it gets damn near impossible to kill a full built tank at times and especially if they get ahead. NOW! That being said, I do not believe that a champions main damage output should EVER be true damage, EVER. So when I end up building 300 armor and 6000 health the death recap should never show that true damage was over 40, 50, or even 60% of the damage dealt.
My proposal is that true damage on TD sustain champions should never be able to exceed 2x the combined damage dealt from all other sources. (Auto attacks included.) This way it's still very much powerful as it should be against tanks, but it prevents vayne from doing 6000 damage in less than 10 autos. And master yi can't just rely on Attack Speed builds and build little to no AD.
The Attack speed on-hit abuse from rageblade needs to end, and since we can't get rid of phantom hits I would argue that this limit would be reasonable to say the least.
Please note that champions like Camille, Darius, Zoe would not be subject to this limitation as they rely on either one specific source of it (EX: Zoe E and Camille Q) or in Darius case it's his entire identity in the form of the rare pentadunk. Furthermore this wouldn't effect conqueror at all, as it's damage will never exceed or even reasonably reach the limit set in place.