Known superhuman powers: Heat immunity; plasma generation; and "plasmakinesis" or a limited degree of conscious control over the paths his plasma travels and the shapes it assumes
Skills: Computer programming; demonology; plasma physics; French and Italian

History: Croswell Tech. was orignally a small repair shop owned and operated by Julian Croswell, Sr. Then, out of the blue, Johnathan Croswell shows up claiming to be a long lost brother. He had money so no one argued with him. Using Jonathan's money and good deal of underhanded, sneaky tricks, Julian began to build his repair shop up into the multibillion dollar corporation it is today. Julian Croswell, Jr., grew up a rich, spoiled brat and under his uncle's tutelage learned to be a bloodthirsty businessman. On his twenty-fifth birthday he had his father assassinated and took control of the company. He married his high school sweetheart, a Spanish heiress and a mutant precognative, and a few years later they had a still-born daughter. After the death of their first child, Maria told Julian that each child they produce would bring death on their household. She was right, and when Julian Croswell, III, was born a couple years later, Maria died in childbirth. Julian's demonic appearance has been present sense birth but due to his father immense resources and numerous connections to various undesirable elements worldwide he was able to lead a "normal" life with an image inducer. Julian grew up bitter and resentful that his parents were never there (mother was dead and father was working) but he also grew up spoiled as had his father before him. When his powers emerged, he burnt his boarding school to the ground accidentally killing about twenty people. His father covered it up of course and to this day no record of the school ever having existed exists. Meanwhile, Jonathan was always one to spot and opportunity so he decided to abandoned his first protege and take Julian, III under his wing. On Julian's twenty-fifth birthday, like his father before him, he took over the company, but unlike his father he simply had Julian Croswell, Jr. committed. Once he got his hands into the family business he immediately went to work on making Croswell Tech. (and the numerous less than legal activities the Croswells are involved in) more profitable. One venture of particular interest was the investment his father had put into one: Muir Island Research Facility. He was intrigued and sought to learn more about Moira MacTaggert and her little operation. It was through these investigations that he learned of the existantce of Excalibur and decided to approach them about getting on his payroll. He found the team under the leadership of Tremor and succeeded in weaseling his way into their midst. However, the team disbanded after some conspiracy with a clone of Tremor. Julian was approached by Aaron Bryce, who offered him the position of Red King of the reformed London Hellfire Club. The condition of which was that he gain an association with the new Excalibur. His first attempt failed, but weeks later he presented a more sugarcoated version of himself and managed to become involved with the team in the middle of a crisis. He "poisoned" Excalibur's scrying pool with a potion given to him by the Hellfire Club to prevent them from gaining knowledge of their plans involving the Phoenix until it was too late. Black Tom wreaked havoc in the English city of Leeds by baiting Excalibur through taking a city councilman named Ronald Amblin hostage. Excalibur pursuit of him damaged much of the new city structure, the Heaven's Gate Tower, which is what Brimstone hired him to have down. In the end, Excalibur caught up to him and he was arrested. Black Tom was broken free from jail by his partner, the Juggernaut. He then went to Brimstone for payment, who tried to back out of their deal. Tom had Juggernaut convince Brimstone otherwise. Aaron Bryce released the Hellfire Club's Scribe to leak information to Brimstone that would provoke him to betray the Hellfire Club and alert Excalibur to their plans. Gryphon was intercepted and held captive by Brimstone, who manipulated the beast within him until it was out of control and released him to attack Excalibur, using him in a plan to topple the Hellfire Club. In the end, Brimstone seemingly came out on top and even got to murder that prick Aaron Bryce. Excalibur member, Twitch, interupted his celebrations, however, with the news that he had managed to appropriate Brimstone's finances leaving him all but penniless. Brimstone was shortly thereafter contacted by Black Air with an ultimatum: Join them or die. Unwilling to be anyone's pawn, he chose the latter option and was gunned down on the front lawn of his own property.