So there is this Rogue class feat called Slippery Mind ( https://nwn.fandom.com/wiki/Slippery_mind ) which allows your character to roll their save again if they fail one against mind-affecting spells.
How about this kind of ability would replace Immunities on most/all classes and items?
Fear Immunity -> You instead get to reroll your saves vs fear
It might make sense not to touch some forms of immunity, such as undead obviously remaining entirely immune to poison and disease.
But all things considered, this might be a good compromise between being totally impervious to X and totally scrapping what some have already invested in (for instance, having put a lot of time, coin and effort into runing and 5%ing Immunity-granting items).
Thoughts?