Chaeronia

The planet featured in Dark Adeptus (Grey Knights 2) by Ben Counter. A former Forge World, it was taken into the Warp for over 1000 years warp-time, while only 100 years in real-time. It is ruled by the Dark Mechanicus, although there are still a few loyal Adeptus Mechanicus troops. It contained an STC Titan, which was destroyed by the Grey Knights. It is likely that the planet was destroyed by Exterminatus due to the extent of tech-heresy that encompassed the entire planet.