'Amber egg clutched by Rennala, Queen of the Full Moon. Great Rune of unborn demigods. Perfects those who have been born anew. Children born anew by Rennala are all frail and short-lived. Imperfect beings, each and all.' Rennala, after Radagon left her to marry Marika, retreated to the heart of Raya Lucaria with a clutched amber egg and a private grief. The egg is the Great Rune of the Unborn, an artefact unlike any other Great Rune in the canon : it does not commemorate a victory. It commemorates a refusal. Rennala uses the rune to perform the canon's only documented rebirth : she lets a Tarnished pay her, in larval tears, to redistribute their attribute points. The mechanic is the trick the lore hides in plain sight. Rebirth itself, in this world, is a lesser act than birth. Rennala can re-make the body. She cannot make the soul whole.

'Children born anew by Rennala are all frail and short-lived. Imperfect beings, each and all.' What Rennala is grieving in her library, what the egg holds, is the demigod children she would have had with Radagon if Radagon had stayed. She practised her rebirth-craft on lesser souls, the Tarnished, the wandering glintstone-corpses of the academy, because she could not perform it on her own demigods. Radagon's children with Marika (Godwyn, Morgott, Mohg, Malenia, Miquella) all died fates Rennala's craft could not reverse. The rune in the egg is for the children that never came. The Tarnished can take it from her after the boss-fight, but it does not function as a Great Rune until it is restored at a Divine Tower, and Rennala's tower is not, in the canon, restorable.