Myconids! psychedelic mushroom people. avoid using the drow, they are played out. Try Duergar instead.The party can think they are dwarves at first. The Duergar encounter the party and pick a fight. If the Duegar win, they can take the players prisoner and use them to kill/clear out a myconid colony. If the party win (which they should, these creatures don't want to die) the Duegar beg for their lives, saying it was all a mistake and you have to be aggressive in the underdark. They say party is strong and ask if they can help the "dwarves" clear out some monsters from a cave near the "dwarves" home. These monsters are actually the myconids.
Myconids are peaceful, and are being eradicated by the Duergar for sport and territory. However, the myconids cannot speak and have to communicate their predicament to the party using visions induced by psychedelic spores. It will be up to the party to decipher the meaning of these visions and decide whether to help the Duergar, who will just turn on the party once the job is done, or the peaceful myconids, who can be a tremendous help in guiding the party through the underdark.