Sauna

Heat rises from an enormous oval stone set into the floor of this chamber. Discarded skins are heaped around it, and shelves underneath it are lined with jars. A snake-headed yuan-ti sheds his skin while two strong, bare-chested human men with spears look on.

The oval stone is 8 feet tall and made of porous rock. Situated atop a volcanic vent, it transfers heat evenly throughout the room. The yuan-ti come here to shed their skins and polish their scales.
Thirty jars line the shelves underneath the oval stone, and each one contains a scented ointment that yuan-ti use to keep their skin supple and to ease the shedding of their skin. The ointment is not valuable.
Unless they have been fought and defeated elsewhere, two enslaved men (NE male Chultan human gladiators) watch Yahru (pronounced YAH-roo), a type 1 yuan-ti malison, as he sheds his skin (a process that can take up to an hour). Yahru is Ras Nsi’s spymaster, and he doesn’t like to be disturbed. Characters passing themselves off as yuan-ti purebloods are instructed to leave the room at once. Enslaved characters are ordered to smear ointment on Yahru’s skin to expedite the skin-shedding process.
Yahru abhors physical combat, and he values his bodyguards too much to risk their lives in a pointless battle. Unless the characters provoke a fight, he tries to find out more about them and learn any secrets they might possess, while providing as little information as possible. If Yahru obtains information that would clearly benefit Ras Nsi or Fenthaza, he chooses which superior to bequeath it to. Yahru enjoys playing them off against each other.
If his bodyguards are defeated and he is facing death, Yahru offers small bits of information for the promise of freedom. In addition to the layout and defenses of the temple, Yahru knows the following:

• Ras Nsi commands the yuan-ti of Omu, but his command is tenuous. The high priest, Fenthaza, is Ras Nsi’s chief rival.
• Ras Nsi is slowly being eaten away by a magical disease for which there is no known cure.
• Ras Nsi has made a pact with a powerful lich named Acererak, who conquered Omu long ago and built a tomb beneath the city. The tomb’s entrance is marked with an obelisk. (Yahru can provide directions.)
• Acererak slew the nine gods of Omu before enslaving the city’s human and minotaur inhabitants, which he used to build his tomb.