Harbinger of Doom, is the final boss of Wolfenstein RPG (in the level "Harbinger"). He is a paranormal monster that comes from another dimension to serve as Harbinger of Apocalypse. However, B.J. defeats the demon after a lengthy battle using the Spear of Destiny. He then tells B.J. that he will continue to fight his descendents (B.J. Blazkowicz III, Stan Blazkowicz) in the future, which takes place in the events of Doom as the Cyberdemon.
Some point in the future, a Marine (apparently named B.J. Blazkowicz) killed a cyber demon with a soulcube not long after he was sent to Mars (Doom 3). Later after getting some psychological treatments on earth, he returned to Mars, where the evil Dr. Kronos created the Cyberdemon again by combining UAC technology with the Harbinger's flesh. It was when it passed through the portal from Hell. UAC records state that there were no survivors. However, following this the Marine returns to work on Mars (but this was not the last time he would fight the forces of hell or a Cyberdemon). Note: The Doom RPG website confirms that the Doom Marine in Doom RPG is the same character from Doom, Doom II, and Doom 3, and that the game is his 'return to Mars'.
You have to save as many ability boosting serums and health packs as you can! You will really need them here, and actually, it is impossible to win without them. The first step is to move to him and attack him with any weapons you've got. You'll automatically run away. When you return with the Spear, attack him, boosting yourself with serums and restoring health when needed. Ultimately, he will summon a few Tormentors. Kill them, then proceed to the blood pool. Stand on it, so the demon won't be able to restore his health anymore. Then, strike him with the Spear, using as many serums and medkits as needed. The boss is much harder than any enemy you encountered before, it is even hard to hit him because he evades most of the attacks, but if you have enough of medication and serums, you'll crush the beast.
Behind the scenesEdit
Harbinger is, in fact, a reference and a "guest character" from Doom video game series, being nearly exact copy of a Doom boss enemy Cyberdemon. The limbs which the Harbinger loses are the same which are prosthetics in the Cyberdemon (a rocket launcher instead of the left arm, a stump on his right leg). His title, Harbinger of Doom, hints that both Wolfenstein RPG and Doom are set in the same universe, putting Wolfenstein RPG in the same continuity as the Doom RPG series (Doom RPG, Doom II RPG), and according to the website the entire Doom series including Doom, Doom II and Doom 3.
Doom II RPG is in fact advertised as the sequel to Wolfenstein RPG, and Doom RPG.
The Cyberdemon actually appears in both Doom RPG, and Doom II RPG (although there is no indication they are the same individual and both die in the same spectacularly gruesome way), and Sarge and the Marine are separate characters, thus there is no way to know which 'encounter' is the one prophesied by the harbinger (although Doom RPG at least suggests how the particular demon species were enhanced with cybernetic implants). He's also a very strong enemy in DooM