Physical Damage Immunity

Physical Damage Immunity (commonly abbreviated as DI) is a percentage reduction of damage taken from any source of physical damage. It is applied before damage resistance and damage reduction (soak). Physical DI's scaling has been changed significantly on SPL due to a vast number of DI reliant classes, many items and more in order to preserve balance. Some effects mimic or provide DI, but not directly, which makes the reduction multiplicative with DI. For more info on other sources of DI equivalent effects, see Feats & Systems

As a note, elemental damage immunity scaling continues to be additive and can reach 100% damage immunity.

The SPL formula for Physical Damage Reduction is:

x = Immunity %
x / (135 + x) = y
100(y) + 0.5 = Z% immunity

To survive something as deadly as tanar'ri, you gotta be like an onion, blood, you can't just use one thing to defend yourself. Like an onion, ye? Wiggler concealment, armored resistances, damage immunities, might even be quick on your step to dodge something, whatever those greybears babble on about. If anything, being mighty meaty like an ogre helps, basher.

Table Examples

If you're looking for a quick reference table on how much vanilla DI is equivalent to SPL DI but without checking a graph, this table is for you. If you're looking for graphical examples, look below.

Ingame/Vanilla NWN DI	SPL DI
10%	7.9%
20%	13.9%
30%	19.18%
40%	23.86%
50%	28.03%
60%	31.77%
70%	35.15%
80%	38.21%
90%	41%
100%	43.55%

Graphical Examples

Often graphic and visual examples can be of help to players who do not enjoy calculating every single detail. These graphs depict the dependence of the NWN damage immunity (horizontal axis) and the actual DI (vertical axis). Both vanilla NWN DI and SPL DI are depicted to give a perspective on the differences.

The orange line is the old DI scaling, the red line is the new scaling. Eg. at 100% DI, characters on SPL actually get ~43.5% DI, while at 40% DI, they actually get ~23.9% DI.

This is a graph of how much damage a character would take from 100 damage, depending on their DI before (orange) and after the change (blue) to the formula. At 100% DI, a vanilla NWN character would take 0 damage. On SPL, they would take ~56 damage.