In his original appearances, it was left ambiguous as to if he was truly supernatural or simply a charlatan where-as later comics would make him explicitly magical.
Deacon Blackfire was a con-man and cult leader and over 100 years old at the time of his death, despite appearing much younger. He had discovered the secret to eternal youth, bathing in buckets of human blood. Blackfire craves power and destruction, and orchestrates his movements toward these goals. During The Cult he forms an army in the sewers beneath Gotham City, largely composed of the homeless and derelict. Blackfire uses this army to begin a violent war on crime, which escalates into him taking over the entire city, resulting in it being isolated from the rest of the country. Blackfire captures and brainwashes Batman, temporarily making the Caped Crusader a member of Blackfire's cult. Batman eventually breaks his conditioning, but its after-effects make it difficult for him to capture Blackfire. After a brutal search through the sewers with Robin, Batman confronts Blackfire, who demands that Batman will kill him, making him a martyr. Batman refuses, and instead savagely beats Blackfire in front of his army. Blackfire's army turns on him and kills him.
Deacon Blackfire is one of the many villains raised from the dead in Gotham City to join the new Black Lantern Corps as zombies during Blackest Night. Along with Abattoir, KGBeast, Blockbuster, King Snake, Magpie, The Trigger Twins, and the Ventriloquist, he has received a Black Lantern Ring. He has been seen terrorizing the city, and tearing out the hearts of innocents in the churches to feed on their emotions and life force when they are feeling the most compassion.
The Cursing of Gotham City
The spirit of Deacon Blackfire attempts to resurrect himself into the body of a kidnapped boy in Detective Comics 982.
Powers and Abilities
In Other Media
The "Blackfire Cult" is mentioned as being an ancient society in an episode where one of their knives is involved in a murder.