One of my players has a Yuan-ti Pureblood character. We've read somewhere that poison immunity extends to many substances and we've gone with this interpretation, for instance we're considering this character to be unable to get drunk.
So I've been wondering, would such a character be affected by Myconid spores? Of course some of the effects mention that the target is poisoned, and those would be out of the question.
But what about more 'innocuous' stuff like the Rapport Spores? The monster manual does state that undead, constructs and elementals are not affected by them. These are all creatures who are traditionally immune to poison, yet they could have stated that the spores don't work on all poison-immune creatures, and they didn't.
So would Rapport Spores and the like work on our Yuan-ti?