Yuan-ti pit masters were mostly humanoid in form, but had many snake-body-like tentacles in place of arms.
Pit masters were traditionalists who always preferred a slow, cautious approach in any matter and opposed any reckless behavior. They felt that they were the most capable of achieving the goals of the yuan-ti.
Like other yuan-ti, pit masters were immune to poison and resistant to spells and other magical effects. They could turn into a snake and back at will. Pit masters could also innately cast the spells animal friendship at will and suggestion thrice each day.
As priests of Merrshaulk, yuan-ti pit masters knew the cantrips eldritch blast, friends, guidance, mage hand, message, and poison spray, and the spells command, counterspell, hellish rebuke, invisibility, misty step, unseen servant, and vampiric touch. They could only cast two spells each day, however.
Additionally, once each day a pit master could cause five creatures within 60 feet (18 meters) of it that it could see to collapse into a magical sleep for 10 minutes.
Pit masters did not use weapons or armor, instead relying on their naturally venomous fangs to deal with enemies.
Yuan-ti pit masters were priests of the ancient yuan-ti god Merrshaulk, and they sacrificed humanoids to him in order to rouse him from his slumber. They were also heavily involved in the long-term plans of the yuan-ti to take over humanoid governments and also in the efforts to protect their own cities from discovery and attack.