During the First Pacification of Luna in ca. 798.M30, the very first campaign of the Great Crusade, Heliosa-54 recognised that her forces would not be able to save Luna from conquest by the Space Marines of the newborn Imperium of Man.
Determined that the Emperor would not claim the Magna Mater, the greatest of the Selenar's genetic engineering technologies which was said to be able to create new life, she entrusted the artefact to her confidant, the Selenar gene-witch Ta'lab Vita-37.
Heliosa-54 ordered Vita-37 to go on the run from the Imperial forces to protect the artefact before she erased all of her memories of her fellow gene-witch so that the Imperium could not learn the wherabouts of the artefact.
Once this was done, Heliosa-54 surrendered Luna to the Emperor and asked him to "call of his wolves." It was this comment which would give the XVI Legion of Space Marines who had participated in the assault their original cognomen of the "Luna Wolves."
For all her efforts, however, the Magna Mater did eventually fall into the hands of the Imperium. The artefact was used to store the most pure copies of the genomes of the twenty Primarchs known to exist.
- Siege of Terra - Sons of the Selenar (Novella) by Graham McNeill, Prologue