Baron Deathmoor is traditionally a lieutenant of the Vampire King Cornello (and presumably Vladimir before him). The Baron is noted to be extremely powerful, even compared to his fellow lieutenants according to both The Rahjs and Rygax, though he requires the blessing of Oluana to attain his full potential. Also of note is that Deathmoor's abilities require that he remains alive, as they would not function for an undead that does not posess life force.
Deathmoore has three major known abilities granted to him by Cornello, all of which are very powerful. Unfortunately for the user, each ability drains their life force, effectively causing them to age 6-8 years on average. To mitigate this, Barons Deathmoor typically gain ageless immortality though Oluana's blessing.
Perhaps Deathmoor's most notable ability, Soul Shield allows him to create a translucent physical barrier to block incoming attacks. The shield can be destroyed, however Deathmoor can refresh it quickly enough that he only takes damage from hits that first penetrated it.
In mechanical terms, the shield is 100 temporary hit points, the user can refresh it at will, regardless of turn order.
Cone of Cremation
Cone of Cremation is Deathmoore's primary offensive ability, allowing him to project a huge and powerful maelstrom of fire and dark energy.
In mechanical terms, CoC seems to be a 30° cone that travels 500ft, dealing 20d6 damage, half fire and half negative energy (fire is applied first if relevant). Targets can save for half damage, but if they fail their save, they are thrown 500ft to the end of the cone, taking additional damage in the process.
Used for dealing with a single target, Freeza Beam is a more concentrated release of the Baron's life energy. Manifesting as a thin beam from the Baron's finger, it nonetheless demonstrates devastating penetrative power, passing through multiple objects including a hill upon missing its target.
In mechanical terms, the beam appears to be a save-or-die spell.
Baron Deathmoor's nature as an archetype rather than an individual means that his history is long and concerns more than one person, though only two previous Barons Deathmoor are known.
The most recent person to hold the title of Baron Deathmoor was the (former) Baron of Woodbridge, a small fief within the County of Midgarde within the Kingdom of Vistria. The Baron made some kind of bargain with the Vampire King Cornello, sacrificing the lives of the roughly 10,000 people living in his barony in exchange for supernatural powers and eternal life. The new Baron Deathmoor recieved the powers that he was promised, but was attacked by the party while waiting for the Oluana Spring to grant the blessing of immortality that would make him a fully-fledged Deathmoor. Baron Woodbridge-Deathmoor died of old age when he was forced to use his abilities to defend himself. He was physically about 105 years old at time of death.
The previous holder of the Baron Deathmoore title, this individual was presumably granted immortality by Oluana and held the title for some time. Fairytale-Deathmoor was killed by Rygax by unknown means at least some decades ago, possibly even before the death of Vladimir. This Deathmoor was also the subject of a number of tales told by William Black to his son Reginald as a child.