Hey guy’s,
guess the title is pretty much self explanatory. Does anybody know if that’s a thing ?
Thanks for the help !! 
This works as well as different resistance reduction: flat stacks with percentage, highest of percentage have priority.
I can translate my post, once prepared for ru-forum, later.
UPD.
Damage reduction (DR)
There are 4 types of damage reduction in the game:
Percentage of total damage (X% reduced target’s damage) - red icon of a broken sword
Absolute of Total Damage (X reduced target’s damage) - red icon of a broken sword
percentage of Physical damage (X% reduced Physical target’s damage) - yellow icon of a broken sword
Percent of elemental damage (X% reduced Elemental target’s damage) - blue icon of a broken sword
They all work exactly the same way as RR.
Reducing the same damage does not stack, but the maximum is effective.
Reductions of different types work in parallel
For example, if you have a 10% reduced target’s damage and a 18% reduced Physical target’s damage, the physical damage of enemies will be reduced by 18%, and all other types by 10%.
Absolute reduction is added to the percentage reduction and applied after it, in addition reduces the damage from each source by the nominal value.
For example, if you have a 100 reduced target’s damage, enemy’s attack with 200 phys.dmg and 200 fire dmg will deal 100 phys.dmg and 100 fire dmg
Thank you, that helped a lot !!!