Was just thinking about this and I should really know how to figure this out myself, but:

What's the total damage reduction on a physical tank buster using Raw Intuition + IB + Vengeance?

Similarly, what would be the total damage reduction on said tank buster with Sheltron + Sentinel + Rampart?

I know Sheltron is affected by which type of shield you're using, but let's just assume 20%. I also know that PLD's would be higher even with the lower % shield, but I'm curious how big the difference is.