Damage done is affected by:
PV protection (see below)
Armor and spell resistance
Elemental balance
Good versus evil balance
World effects on magic: ±5% change depending on world and damage type
Underwater modifiers
Protection
A formula for damage protections derived after extensive tests by many players is:
A = B × C × (1 - D) × [1 - (E + F + G)] × (1 - H),
where
A = Damage
B = Maximum Damage
C = Elemental Balance
D = PV Resistance
E = Spell Resistance
F = Equipment Resistance
G = Equipment Vulnerability
H = Racial Resistance or Vulnerability
PV protection
Damage types and how much armor protects against them:
Acid — Protects strongly
Asphyxiation — Armor has no effect
Cold — Protects moderately
Disintegration — Protects somewhat
Electrical — Protects very little
Fire — Protects moderately
Harm — Protects very little
Holy — Armor has no effect
Illusion — Armor has no effect
Physical — Protects very strongly
Poison — Protects very little
Primal — Armor has no effect
Psionic— Armor has no effect
Sonic — Armor has no effect
Unholy — Armor has no effect
Underwater damage
Asphyxiation damage is 50% higher underwater
Sonic damage is 25% higher underwater
Electrical damage is 50% lower underwater, but it damages all being in the room, including yourself and your party
Cold spells have chance to hold underwater (testing needed).
Fire damage is 90% lower underwater