I have a group planning to run Emerald Spire. One wants to be a toxicant alchemist, another a psychic. There are two floors filled with serpentfolk who are immune to both poisons and mind-affecting effects. Are there any ways to bypass immunities or should I just get them off those characters?
There are ways for mind affecting in certain ways, but not that I know of for poisons. Unsure if there's any way to bypass specific "no sell" immunity like the Serpentfolk have, though, most of the immunity bypassing stuff is geared around getting by incidental immunity (immunity by virtue of being undead, for instance).
The Psychic will be fine unless he loads up with ONLY mind affecting save or suck spells. The Psychic list has buffs and other types of spells too, if he over-specializes that's his fault.
The Toxicant...I'd ward him off it as a matter of principle, because even creatures that AREN'T immune can probably shrug off poison easily, and even the ones that can't probably won't live long enough to be debilitated by them.