Reverend Slaggingham was created by writer John Ney Rieber and artist Gary Amaro in The Books of Magic issue 9 in 1995.
Major Story Arcs
Slaggingham grows up in the Victorian era, and stays alive for more than 140 years due to steampunk-level cybernetics. He is a cantankerous, manipulative man who lives by his watch.
In the modern era, he runs a kingdom in the sewers under London, selling magical snake oil to passersby through an army of assistants. He often collects people's souls, including that of Auberon, in small globes. On rare occasion, he works with people who live aboveground, such as Tim Hunter's childhood friend, Jimmy Morehead. Morehead won't spy on Tim, so Slaggingham kills him by sealing him with a gutta-percha gun, then sells him to a sewing shop.
When Daniel, a boy who also grew up in the Victorian era, but has lived in another dimension for years and so has not aged, runs away to the sewers, he finds Slaggingham. Slaggingham recruits him to work along with his other associates such as Sister Staylace and Brother Salamander.
Various beings created by Tim Hunter also live in the sewers along with Slaggingham's crew, such as the Queen of the Buggers and Awn the Blink.
Slaggingham's big plan is based on the idea that there is a finite amount of happiness, so he wants to make the upper world unhappy, and drain whatever happiness they have down to the sewers using a magical machine that he has been working on for 77 years. He uses the people whose souls he's captured to work on his machine.
He uses another machine to give Daniel powers by revealing the truth of his dirty soul. Daniel attacks Tim and Daniel's ex, Marya, but loses.
Awn the Blink finally explains to the Reverend that you can't suck happiness out of the air, and Slaggingham, in despair, rips apart his mechanical heart. When he begins to break down, his underground kingdom does as well, and it floods. His associates leave and find new paths in life. For instance, Sister Staylace becomes a good friend of Tim's. She helps Auberon get his soul back.
Daniel survives the flood, and takes Slaggingham's head with him. He talks to the head to keep sane, and Slaggingham insanely talks back, his parts clearly on the fritz. Slaggingham thinks he talks to god and the devil.
Much later, Slaggingham's head continues to lay on the rooftop where Daniel last left it. Now, he does actually see angels and devils--they are in a war.
Circe chats with him about the war, and then takes his head along with her. He now constantly and incoherently (but accurately) prophesies the future told to him by the Queen of Wounds and her more angelic counterpart. Slaggingham and Circe watch as the Queen and her counterpart, Tim, Cyril, and Araquel among others go through a complex apocalyptic storyline.
Slaggingham designs a machine to capture all the angels and devils, and Awn the Blink creates it. Slaggingham's head is attached to it. It works, and captures the god and devil figures, which then merge and transmute into Spinning Jemmy.
Much later, after Tim has defeated Barbatos, Slaggingham and Circe are seen driving along happily together, Slaggingham's head attached to her convertible.
Powers and Abilities
Reverend Slaggingham is a cyborg. He can survive with only his head remaining.
He can project a gun out of one eye.
He is capable of creating a variety of machines and magical objects, some of which don't work (like a machine to suck the happiness out of the surface world) and some of which do (like a machine to transform Daniel into a magical creature, or a machine to capture armies of angels and devils).