All took the mask willingly. To those not understanding what it entails, the mask is inert. It is made of thick stone. It depicts a snarling dog.
Once donned by the willing, it cannot be removed. One wearing the mask is utterly loyal to the one who offered them the mask. If this chain is broken, they are free but retain their subordinates. All await this day, but are powerless to hasten it.
Domesticated animals and crops despise them, and wither in their captivity.
This is one of the paths a man could take to leave mortality behind.
HD 1* / AC as Armour / Damage as Weapon
*Supernatural HP - the body is as loyal as the mind, unwilling to die despite horrific wounds.