Souls in the Dark
This campaign will use the following variant rules in combat:
Called Shots: Called shots will be used using the rules presented here http://paizo.com/pathfinderRPG/prd/ultimateCombat/variants/calledShots.html . The feats presented here are available to PCs.
Critical Hits: Most undead, plants and constructs are subject to critical hits. Individual creatures may be immune on a case-by-case basis. Oozes are still immune to critical hits.