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Chapter 2: Tools / Building Creatures

Immunities, Weaknesses, and Resistances

Source Gamemastery Guide pg. 63
If it’s highly thematic for a creature to have an immunity, weakness, or resistance, consider adding it. Table 2–8 lists the ranges for weaknesses and resistances by level.

Immunities are generally reserved for creatures made of an unusual substance (like a fire elemental being immune to fire). You can also give an immunity if a creature’s biology or construction would logically cause it to be unaffected (like a mindless creature’s immunity to mental effects).

If the creature should be hard to affect with something but the conditions above aren’t true, give it a resistance instead. For instance, a giant octopus isn’t actually made of cold water, so it wouldn’t be immune to cold, but its life in the ocean depths make it resistant to cold. You’ll typically use the lower end of the value on Table 2–8 for a broad resistance that applies to a wide range of effects, like “physical 5 (except silver)” and the higher end for something narrower, like a single damage type. A creature with a resistance, especially a broad resistance or a physical resistance, usually has fewer HP.

Giving your creature a weakness adds flavor to it and greatly rewards effective player tactics once your players identify the weakness. The weakness should apply to one damage type or phenomenon and use the high end of the scale. Creatures typically have at most one weakness. If a creature has a weakness, especially to something common, give it additional HP. The amount of additional HP might depend on how tough the creature should feel if the PCs don’t exploit its weakness; a tough creature might have additional HP equal to quadruple the weakness value. A creature with a hard-to-exploit weakness might have additional HP equal to the weakness value or less.

Table 2–8: Resistances and Weaknesses

LevelMaximumMinimum
–111
031
132
252
363
474
584
695
7105
8116
9126
10137
11147
12158
13168
14179
15189
16199
171910
182010
192111
202211
212312
222412
232513
242613
The combination of more HP and a weakness has a different feel from standard HP with resistances. If the creature being an impervious tank really fits its theme, use a resistance with an exception, such as “physical 5 (except silver).” If, however, it makes more sense for normal hits to get through and the creature to simply have great staying power, use more HP and a weakness. Skeletons and zombies are a good example of the difference between these styles. Skeletons have resistances because they’re bony and hard to hurt. Zombies, on the other hand, have more HP and a weakness to slashing damage—they’re tougher, but their bodies aren’t built to deflect weapon attacks, and slashing attacks can rip them up quickly.