Damage taken as

Does "damage taken as" counts as dmaage mitigation ?

For example if i do damage shift for phys->fire does it counts as physical mitigaion for game ?

If you have 0% fire resistance and 100% physical taken as fire, then you mitigate 0% of that damage. You reduce damage taken through resistances and damage reduction like Fortify, Spell Suppression etc.

Damage taken as shifts HOW you take damage.