The First Sanctum

It is the remote motherhouse of the Luminarite Creed and the Arch Luminar's true seat. The hymns describe it as "terraces of white stone, each level narrower than the last, until the highest chapel seemed less built than sharpened out of the sky". Hollowborn have been sighted closer to it than ever before.

It is not the Lower Sanctum beneath Luna's Spire.

From the books

The Sanctum's authority reaches Luminglade through Brother Adresin, its envoy and the public voice of the Arch Luminar. He appears on the Council of Masks' balcony in pale, spotless robes with a sliver of polished luminarite at his throat, and his Sanctum-white coat is described as too fine for Luminglade. To Nyssa, the motherhouse is a distant power forever reaching toward the Spire, convinced it can tell everyone else how to hold their gods.

The Spire tithe runs under its name. Brother Kael presents the chosen Fae youths as volunteers honoured to serve in the First Sanctum for a decade, clothed, fed and sheltered under the Spire's light. In practice the envoy secures consent, Council seals and roads, while Kael receives whoever arrives at the other end. Kael's orders carry Adresin's countersign beneath the open eye of the First Sanctum, and Kael reports that the Sanctum regards the king's marriage to a human woman from the slums as a fracture. If the Solastis line cannot keep its purity, he says, other vessels must be prepared.

When the candidates are taken into Luna, they enter not through the white terraces of the hymns but through the city's underside: service corridors, drainage stone, locked devotional doors and passages built for prisoners and relics. The undercroft borrows the First Sanctum's authority and none of its distance. A Sanctum official calls the arrangement a mercy of geography, in which the motherhouse keeps prayer above the dirt while the Spire's necessary work is done below.

Kael's death does not end the threat. Kael himself boasts that if he is allowed to work, the First Sanctum inherits everything. Afterwards Leth Serane looks toward the road beyond Luna and the white motherhouse waiting with clean hands. He warns that templars would be easier subjects than Fae, since doctrine has already shaped their souls, and that Kael's notes do not teach the Sanctum how to strip humanity from the unwilling but which parts no longer need removing.