User blog comment:GutsyTick/Zamael/@comment-6719710-20150126094848/@comment-26044269-20150126124106

Since all of Zamael's damage is physical, I personally don't think it would be a problem.

Besides, the whole purpose of putting in such a powerful, yet non-scaling passive was to promote building more defensively on Zamael rather than offensive.

This would ensure that Zamael would not be able to blow up people with a fully charged Ruin and Shift proc in normal conditions, while still enabling him to be a tenacious threat in teamfights (although 500 + 200% AD true damage onto a squishy would be hilarious to see in a real game).