For mostly all resistance effects you simply add upp the total resistances. That is:
phys res = 0%
Amp dammage = -100%
Ber rune = +8%
Vampire gaze = +20%
String of ears = +15%
Stormshield = +35%
Shaftstop = +30%
phys res = 0 -100 +8+20+15+35+30 = 8%
when getting 100 phys dammage you would get :
dmg = 100 * (1 + 8/100) = 108 dmg
Cold mastery does not work this way however. As far as i know it lowers the resistance by the % amount given. so with 50% cold mastery against 75% cold resist you would get a total of : 37,5% cold resist. In Hell / nigtmare the cold mastrey is applied before the difficulty penalty. (ie 200% cold resistance, with 50% cold mastery = 100% cold res - 100% hell penalty = 0% cold res)
I think lower resistance works by simple addition, but im not 100% sure about that.
phys res = 0%
Amp dammage = -100%
Ber rune = +8%
Vampire gaze = +20%
String of ears = +15%
Stormshield = +35%
Shaftstop = +30%
phys res = 0 -100 +8+20+15+35+30 = 8%
when getting 100 phys dammage you would get :
dmg = 100 * (1 + 8/100) = 108 dmg
Cold mastery does not work this way however. As far as i know it lowers the resistance by the % amount given. so with 50% cold mastery against 75% cold resist you would get a total of : 37,5% cold resist. In Hell / nigtmare the cold mastrey is applied before the difficulty penalty. (ie 200% cold resistance, with 50% cold mastery = 100% cold res - 100% hell penalty = 0% cold res)
I think lower resistance works by simple addition, but im not 100% sure about that.