Aeryn Rudel, known as "Blackdirge" or "Blackdyrge", began posting posting templated monsters with rigorously correct stats and lurid backstories on EN World's NPC forum at the height of the d20 boom. He followed this with his "NPC profiles", where he traced the development of a single character from low to very high levels, both narratively and stat-wise. Popular examples include "Grummock, the Gargoyle Assassin" and "Nithrekel, Earth Mephit Fighter NPC through 50 years of servitude".

His next large product, "Metamorphosis: From Dretch to Demon Lord", was a loosely-related sequel to the Nithrekel profile that started in EN World's Story Hour forum. Focused more on the story than the stats, "Metamorphosis" was picked up by EN Publishing halfway through the first book, who released what developed into a three volume novel as a commercial product (in both PDF and print on demand formats).

Rudel's reputation helped launch a career as an editor and a writer, both freelance and under his own imprint as the founder and president of Blackdirge Publishing. His company is active in the PDF market, supporting both d20 and now Dungeons & Dragons 4E.