Recently devoured by Hive Fleet Laviathan these planets should be void of life, noone argued that. But the hope was the subsurface mineral wealth was still intact, this is the Magos' primary mission. However, the newly promoted Magos Explorator Giovanni Amici, leader of this Armada, has a private theory which he has shown to be 67.121212% accurate, that of a STC discovery. Only a few husks of former Imperial worlds are explored in the wake of a hive fleet, and those are have been found to be barren rocks. But the core worlds were, or rather are, different... Homo Sapiens Rotundus had developed an entire civilization there in the dark days before the Emperor, they developed underground systems, tunnels and mines, cities, an Empire. They possessed many STC constructs, even developed beyond them in many ways... the Amici knew many of these paths could lead him to the realm of heresy in the eyes of the Fabricator General, but they were risks he was willing to take.
For he knew the Omnissiah would guide him to these lost treasures.