perception rank 2 special feats, mainly improved improved critical and so on don't work reliably. it could be that the critical system is buggy in general so you never notice, otherwise. after extensive testing, it seems that critical hit confirmation is random. as though there is an invisible and undocumented fortification effect on enemies. with regular rolling, random attacks in the critical range will not roll the required confirmation rolls. they auto-fail. using the trickster's all 20's magic spell, which gives 20's on every d20 roll, resulted in attacks prompting to be confirmed every time, but not confirming with 20's. the minimum amount of failures i've seen with natural 20's was 1. the maximum was all 6 attacks from my merc rogue. roll = 20. confirm roll = 20: "critical not confirmed." after reloading the area multiple times and quitting to desktop to ensure it wasn't a loading error, i tested it lots of times. no effect happens to make it stop confirming at a certain point. attacks fail to confirm on the first hit and confirm on later hits. also they confirm on the first, fail to confirm in the middle, and ends with another confirmation. it's completely random. long story short, don't waste the feats. no mods ever used.

religion rank 2 and 3, greater enduring spells doesn't seem to have any interactivity with the spells acquired from these domains. haven't tested many of them, as most are instantaneous or less than 5 minutes. communal stone skin seemed like a bargain, making sure to get your value out of the diamond dust required to use the spell, but the duration is the original 10 minutes. can't say for sure if it's the spell itself or the way in which you acquire the spell, but it doesn't work regardless.