If a creature attacks a PC with an attack that does 6d6 fire, and also another 4d6 fire from burn if they fail their save, and the PC has, say, Fire resistance 20, when does the resistance apply? Do you A) add the total dmg together first (10d6-20)? Or B) do you take 20 off each separately? I assume A but can't find a rules explanation for one over the other.
A creature with resistance to energy has the ability (usually extraordinary) to ignore some damage of a certain type per attack, but it does not have total immunity.
The answer is B. Per attack. Burn, while triggered by the attack, is part of a separate ability. So it would be 6d6-20 and 4d6-20.