The Hall of the Dawning is a small area added in The Stir of Dawn DLC/update. It is connected to the Ferrous Tree.
This room has a mirror coffin in the middle, and four statues standing beside it. The end of the room houses a Quicksilver, though an iron gate will prevent further passage unless the player is on True Torment mode.
By beating each of the Amanecidas of the Miracle, a golden weapon will appear in the matching statues' hand. Once all are defeated the coffin's lid shatters and a gate on the right side will open, so The Penitent One can pass through. This leads to the final optional boss battle, Laudes, the First of the Amanecidas.
Following Laudes' defeat, this is Jibrael's final appearance, where he rejoices over Laudes finally finding peace as he fades out of existence.