Uh… I don’t think that’s correct. And I don’t know if that’s the exact formula for that.
Why did you repeat the armor mitigation there? And did you manage to get 96% armor mitigation for DoTs without accounting the Iron Attunement? So you actually got 133,5% armor mitigation for DoTs?
If that’s the case, then the formula would be simply 82*133,5%, which would result in 109,47%, no?
@Llama8 help me out here 
Actually I am not so sure now. After reading the description of the Iron Attunement node I am getting confused.
Anyway, the conclusion probably won’t change since both results are larger than 100%.
Remember that non-physical damage uses only 60 or 70% of your armour mitigation value, never can remember the correct number.
I had roughly tested it, not a good setup and I barely remember it, but I think I came to the impression that having more than 100% ‘Armour Mitigation applies to dot’ has no further effects.
Remember that non-physical damage uses only 60 or 70% of your armour mitigation value
I forgot about this. Should have tested with bleed damage. Will test it some time later.
tested again and updated in OP in section “Update 2”.
From my testing it seems to be like this:
If I cap Dots to armor at 100%, and I have armor mitigation at max 85%, I still get around 59% dmg from DOTs. It is not surprising for me and think it works as intended.
Ps. Still not enough to make my sentinel tanky enough on certain corr 600+ level and HP/dps/clear speed lvl, meh 
Would just to another sentinel, maybe with better results 
85% * 70% (because non-physical) = 59.5%.
Exactly!
Now I am really curious about how you got those results!
Did you take a video and then checked it frame for frame and writing down the numbers`?
Or is there a more sophisticated method available?
Are you certain the game is using the Armor DR % → DoT DR% and not the raw Armor value?
I would expect it to be Raw Armor value → DoT Armor value → DoT Armor DR%
The stat does technically say X% of Armor (value), not X% of Armor DR, right?
No, the DoT DR stat specifically says “% of Armor Mitigation also applies to Damage over Time”, not “% of your armor applies to damage over time”… So it should use % armor mitigation.