I've been told plenty of times that raid instances have an armor threshold for tanks. They say if you fail to reach that you take extra damage from bosses. I really want confirmation/clarification on this.
I'm running a protection tanking spec on my conq and dt and in those builds I skip points in iron skin to get improved defensive and further boost my magical mitigations. This means I usually have 5-6% less mitigation than a regular tank build. I'm using protecton build for fights like brothers demo, louhi, thoth amon, emperor, which are completely magical damage fights.
My hesitation is about whether I would fail this threshold with such a build.
I did a small test last night on my conq against emperor. I charged emperor in t4 with maximum possible armor and 57.5% melee mitigation. Then I repeated the same thing later keeping my protection the same by removing parts that don't give protection. I had lower than 40% melee mitigation. In both cases I had the same magical mitigations and boss hit me for the same amount of damage (ignoring crits)
So questions:
Is there a thing like an armor threshold for raid instances like t3 or t4?
If so, does it effect magical hitting bosses? Maybe they have their own magical mitigation threshold that you must pass?
If there exists an armor threshold then it must be above 57.5% for t4? In that case it is a tad bit too high for me to bother passing on dt or conq.
Anybody tested this issue at all or is it just a myth?