Merrshaulk
The Sleeping God

Demon Lord of Serpents, Venom, and Torpor [Intermediate God]

Symbol Cobra's head  
Alignment Chaotic Evil  
Priest Alignment CE  
Plane Abyss  
Worshippers Yuan ti, ophidians, reptile cultists  
Race Yuan ti, ophidian, human (few)  
Sex Any  
Attributes Intelligence 15 -2
Proficiency Groups Warrior, Priest, General 5
Bonus Proficiency N/A  
Preferred Weapon   Scimitar
Allowed Weapons Any 10
Armor Any, no shield -5
Primary Sphere Animal 7
Major Spheres All, Divination, Guardian, Healing (reverse), Plant 37
Minor Spheres Chaos, Charm, Combat, Protection 19
Additional Spells Neutralize Poison (4th level), Regenerate (7th level) 1
Abilities
  No followers  
  Immune to poisons (magical or natural) 15
  Animal Empathy (with reptiles and amphibians only), as the ranger ability 10
5th level Sticks to Snakes (poisonous only, 1/day)
5 (1/day) + 4 (P4) - 2 (5th level) - 1 (2 powers) = 6
6
9th level Poisonous touch: all touched by the priest's hand must save against poison or die, unless they are part-reptile or immune to poison. This ability is unconscious, and can not be suppressed.
10 (continuous) + 8 (P4 x 2, for power ) - 4 (9th level) - 1 (2 powers) = 13
13
  Shapechange into any type of non-magical snake or giant snake (3 forms per day, as druid, the same form can be taken more than once)
15 (base) - 1 (2 levels past 9th) = 14
14
Limitations
  Fanaticism: the priests of Merrshaulk suffer no other priests to live -5
  +5% experience cost -5
  Talisman: human priests of Merrshaulk require a reptile skin torc, specially consecrated to their god  
  Contact: Merrshaulk's priests regain their spells through direct mental contact with their (admittedly sleeping) god  
Raiment No special requirements for reptilian priests, human priests prefer green and brown apparel, and must always wear some form of clothing made of snake's skin  
Animal Cobra  
Holy Days New moon of Luna, blood sacrifice (usually of slaves)  
Notes
The Animal sphere can only be used to affect and/or summon reptiles and amphibians (charm person or mammal is replaced with charm reptile)
Merrshaulk rarely attains a waking state, though he remains aware enough to grant abilities to his priests. Any spell that requires contact with their god (such as commune) will fail or produce a vague response.
Higher level human priests of Merrshaulk begin to take on reptilian characteristics
Most yuan ti priests of Merrshaulk are half-breeds or abominations, usually with human heads
Yuan ti translates to "spirit of the serpent" in their language (a corrupted Suel dialect)
The ophidians are believed to be far older than the yuan ti, and are a race created through Merrshaulk's power
Background
Merrshaulk, the cobra-headed god of the yuan ti, was once a minor demonic power. Centuries ago, his faith began to spread through the ancient Suel imperium, and his power grew. His worship was carried south into the Hepmonaland during the collapse of the Suel empire. His priests built a great empire south of the Tilvanot peninsula, centered around a city built inside a mountain rift. The empire of the yuan ti reached its apex two hundred years before the founding of the Great Kingdom.

Fed by the souls sacrificed upon his altars, Merrshaulk's power grew to levels unheard of amongst demonkind. The empire of the yuan ti waxed in strength for the next two hundred years, and soon was threatening to encroach upon the southern Flanaess. However, as their power grew, their bloodline also became corrupted -- his priests, already reptilian in spirit, took on the outward aspect of their demon prince. This corruption spread throughout the faithful of the Yuan Ti, bringing with it the worst aspects of their lord -- treachery, arrogance, and a growing lassitude. Over the next century, the yuan ti began a great decline.

Just over five centuries ago, powerful forces of unknown nature descended upon the yuan ti's capital, decimating their armies. Their jungle empire rapidly collapsed, and their mountain fortress was lost to memory, known now only as the Forbidden City. The tribes of the Hepmonaland have since returned to the old ways. Merrshaulk himself is now barely a memory -- he lies deep in his Abyssal lair, dreaming of his past glory, and dining on the thousand thousand souls delivered onto him by his serpent priests.

An adventurer travelling into the Hepmonaland will hear legends of the demon-people of the jungles, half-man and half-snake. The yuan ti still live in their ruined cities deep in the jungles of the Hepmonaland, served by bugbears, tasloi, and their human slaves. It is rumored that the Forbidden City yet survives, and that the yuan ti once again dream dreams of conquest and blood.

Sources
Monster Mythology, p. 100 (original source)
Monster Manual II, p. 100
Monstrous Compendium, p. 369
Module I1: Dwellers of the Forbidden City
(the physical description of their god appears on page 6)