How does -% To Enemy Fire Resistance work?

General Discussion
1

fx:
-15 % To Enemy Fire Resistance
and
-20 % To Enemy Fire Resistance
does it add up flat to -35%?

I guess if your merc have equip with - % To Enemy Fire Resistance
it doesnt add up to your equip?

2

Your Items stack up to give you a total -resistances.
Your mercs only work for him

to see how much resistances you have against foes press C/ then expand to show you your stats
In order to break immunes you need either the paladins conviction skill (infinity) on the merc weapon or the necro lower resist skill