Sephlagm

Sephlagm was an irradiated hive world, and is now a dead world. No segmentum, no star system, and no coordinates are recorded for it. Its atmosphere could kill anyone not travelling in a vehicle.

Azrael, as Grand Master of the Deathwing from 917.M41, slew its daemonically possessed governor, and the Dark Angels then evacuated. The world was destroyed by Exterminatus. No year is recorded for that destruction beyond its following his appointment.