recently i found the DAMAGE_MULT attribute actually stacks like this-
(Damage) * (1 + ((1 - A/100) + (1 - B/100) + ...))
rather than the more intuitive multiplicative way:
(Damage) * (A/100 * B/100 * ...)
where A, B etc are the DAMAGE_MULT values (eg 150%, 200%) from different modifiers, or a single modifier stacking multiple times
pretty weird because if i remember right (from testing years ago), other attributes like HEALTH_MULT and ARMOR are calculated in the latter way.... or perhaps i could be wrong about those too
just thought i'd share this