The Devil's Right Hand: The Infernal Emissary. (OSR)

"  In the year 1502 there was a peasant named Pierre Burgot who was tending
sheep while a large and fierce storm broke out. From seemingly out of nowhere
rode three men dressed in black riding upon three black horses. One of the men
called himself Moyset, tall and pale, sunken eyes with long black hair. Moyset
told Pierre he would let his hands watch over his herd and give him great
fortune if he would obey him, Pierre agreed. In the next meeting, Moyset stated
his commands, to reject a so called "god", the false virgin, the baptism and
confirmation. Burgot accepted the demands and swore loyalty by kissing the hand
of the Moyset, which was as cold as the hand of the dead."

Infernal Emissary 

No. Enc.: 1 (1)
Alignment: Lawful (evil)
Movement: 120' (40')
Armor Class: 7/12
Hit Dice: 12
Attacks: By weapon
Damage: by weapon (+2 strength)
Save: C12
Morale: 11
Hoard Class: XVII
XP:  4,400

An Infernal Emissary is a representative of the Adversary on Earth. He is a recruiter of the desperate and a corrupter of souls. The single duty of the Emissary is to collect the signatures and pacts of those willing to sell their souls to Hell for power and favor.

The Emissary is dressed head to toe in black and travels on a powerful black horse. He is often accompanied by minions similarly dressed and mounted. The Emissary is marked by his allegiance to the Powers of Darkness with a pale and sinister cast and a curious and otherworldly deformity such as a coldness of the flesh, as if of the dead, or a blackened hand, as if frost bitten.

The Emissary is drawn to those who are desperate, deranged, or evil. Offering wealth and promises of fulfilled desires, the Emissary will recruit the damned if they accept the Adversary as their Lord and Master, reject all that is good and dedicate themselves to do evil, and finally to seal the pact with a kiss upon his corpse cold hand or sometimes a signet ring or other special item. The damned will be required to attend Sabbaths, to spit out the Host as given in Mass, and other heretical actions to show their rejection of the faithful and their allegiance to the Adversary.

Once the damned are in his debt, the Emissary will meet with them to give gifts such as money and special salves, ointments, or other evil charms to aide them carry out their evil. These items are often ointments to fly, salves or wolf-skin girdles to change into werewolves, poisons to sicken and kill their neighbors, or any other item to war on the faithful and sow the seeds of fear and panic among them.

An Emissary will sometimes preside over the Black Mass and Sabbath's. Dressed in goat, dog, or other animal skins, he will lead the blasphemous and horrible rituals, feasting, and revelry. An Emissary is thoroughly corrupted of soul and damned to Hell. They are evil, and there is no salvation for them.

An Emissary is always wealthy due to his power and status. He will be an experienced traveler, well networked with others who serve the Adversary, and often hold high positions in the community he lives in, using his powers, wealth, and influence to appear as a gentleman and fit into society around him.

An Infernal Emissary has the spellcasting and special abilities of a 12th Level Witch (or Cleric in Fantasy settings). He will have a number of potions, charms, and magic items a appropriate to the setting and the DM's game. If challenged by a powerful force of faith or good he may call upon his Master for aide in the form of a demon, powerful undead, or other servitor if the DM sees fit.
Due to his connections to the Adversary, he cannot be harmed by normal weapons, only those of silver and magic.

His fierce eyes are hypnotic and three times per day he can use them to Charm a victim. If the victim makes his saving throw the Emissary cannot try to charm him again for 24 hours.

Finally, the marked or black hand can be used for a touch attack three times per day. Success causes paralysis as if a ghoul had attacked the victim.

"There is a record of a child werewolf as well. He was Jean Grenier ofAquitaire. His story was more or less like that of Burgot. When his father had beat him, he ran away from home and wandered around the countryside. One evening another boy named Pierre La Tihaire took him to the depths of the woods. According to them, the Lord of the Jungle was there. He was a tall black dressed dark man upon a dark horse. The Lord got off his horse and kissed Grenier with icy lips. In the second meeting both of the boys submitted themselves to the acclaimed Lord who scratched tattoos on their thighs as brands. He brought out a wine bag and gave them a drink. He also presented them wolf skins and an ointment. The Lord taught them how to rub their bodies with the ointment before putting on the fur."

The Emissary's Steed
Especially powerful Emissary's may be mounted on a Nightmare.

Minions
The Emissary may be accompanied by minions, each dressed in black, and riding black horses if travelling or on business.
The Minions are 5 HD Fighters and will fight to the death for the Emissary.