The Darkwatchers are a drow tribe that reside in the Darkfire Crater in Xen’drik. Named by the drow tribes who live in its shadow, this volcano was thought to be dormant, but recently erupted. Unfortunately, the volcano contained hundreds of fiends bound within its magma, many of which have now been released.
Following the Age of Demons, Argonnessen deployed ten dragons to Xen’drik to watch and guard important sites against the potential threat of the giants. The current Red Warden, one of these dragons, is an adult red dragon named Zinshear-Jhodjaros. He was killed when the volcano erupted. His remains are being puppeteered by swarms of hellwasps that emerged during the eruption.
A rakshasa named Kintakathjalil has been reporting back to the Eyes of Chronepsis in Argonnessen disguised as the fallen warden and has so far convinced them that all is well. More fiends remain bound within the crater, including a tiger-headed balor by the name of CylMaaldrake, which the free fiends seek to release.
The Darkwatchers are the only force currently opposing the fiends. They previously served under the Red Warden, and with the dragon slain they have not fared well. They’ve been pushed back into the lava tunnels around the caldera and are constantly assaulted by the fiends.
A shulassakar, Sesstaria (female transcendent shulassakar, she/her), who is primarily in Xen’drik to ensure the Scar that Abides remains bound, has taken an interest in the Darkwatchers’ situation and has begun to help them. She lacks the power to take on the fallen dragon or its minions, but she has taught the drow how to access the power of the Silver Flame, empowering them in their war with the fiends.
Source: Sarhain's Guide to the Silver Flame