these monks show up -
they found reference of a series of resonate bowls that when the lips are stroked in a circle a sound started. A sound that passes back and forth between all the other bowls in the space. Together, they make a magic that keeps a litch trapped. She's a spider centaur litch - and that seems powerful since their society is based around music. Anyway. The song is about to end - and these monks know how to restart the pattern of resonance. They are kinda nerds and calculations are their thing.
but of course, they need a series of adventurers to help them.
They venture their way there. Finding a there are some drug dealers growing thing in the area (one of Monks seemed to know about this sort of thing - he's fom Candet)
They fought some guardians down a hidden manhole like stone. (the same monk would like a trophy head as the other monks always teased these guys about their 1,000 year song theory - which is obviously correct and all)
by the time they get into the room, the song is still there, but slowly winding down. The room is amazing - set in careful places with all makes of bowls. A careful series of steps, lined on the sides with larger bowls lead down to what is obviously a time-frozen pit prison - which is well en-runed.
that's when the one monk ran in, destroyed bowls and pledged himself to the service of the Litch!
The song stops
the portal unlocks
a fight happens on the floor, being careful not to disturb the other bowls. The nerdy monks jump to reset the pattern with the one they calculated.
The legs of the Spider Litch begin to come out of the prison....
the characters clear the crazy monk, and try to restart the pattern. Player characters must help - - - -
the song returns.
the Litch retreats to her magically induced slumber.