References
Duergar have certain immunities:
Immune: paralysis, phantasms, poison
Paralyzed is a separate condition from Stunned, however, and I haven't read anything that says a creature that's immune to paralysis is immune to stuns, but the debate happened at the gaming table yesterday. The case brought forth was Paralysis being a higher form of Stunning – akin to Frightened being a higher form of Shaken.
Scenario
I was a monk trying to use stunning fist against a duergar. The GM said, your stunning fist attempt fails because they are immune to paralysis. I pointed out that stunning is a separate condition. Since the topic turned into a discussion that took up over 15 minutes of game time, I finally accepted his ruling and moved on.
Question
Are creatures immune to paralysis, by proxy immune to stunning?
Best Answer
Paralysis immunity does not imply stun immunity.
Being paralyzed is not an increased form of being stunned. Their sources and actual effects are completely different:
A paralyzed creature…
A stunned creature…
Paralyzed means you are completely frozen in place, whereas stunned means it's like getting hit by a boxer's right cross to the chin — you're so close to being knocked out, you can't properly defend yourself — that you're basically just stumbling around.