Once more, there was a rumbling in the fortress. What was rumbling, few could identify. It was not anything tangible to be felt, and produced no noise to be heard, even to the genehanced ear of an Astartes, or one of the many xenos species that maintained something akin to an embassy. No, it was not a rumbling that any scientist would call such, nothing seismic or mechanical. It was a call, however, and those that needed to hear it, did. A psychic summons, from the Deepest, Darkest Depths of