Since it cant be itemized against to reduce the damage (like AR for AD and MR for AP) with the arguable exception of flat health, it seems a bit too powerful of a damage source to allow it to be doubled every 2 hits.
Mecha MaIphite1 votesHow is health as a counter to flat true damage arguable?
JavelinJoe1 votesit is technically an increase in sustain since it takes a slightly longer time to kill you. Although %Max health would be the same ratio the base damage would not be as effective since it doesn't scale with the same ratio.
Mecha MaIphite1 votesBy that logic, building armor against an AD champion is just an increase to sustain, as it will take longer to kill a target with more armor.
Furthermore, the only instance of %true damage that interacts with devourer is Vayne, and that was addressed when it was nerfed for ranged champs.