Glass Panes of Life and Death

They are currently in Mortuary's possession, part of his responsibilities being the Lord and Scribe of Death, and kept in a vault in the Lord's home plane.
Each pane is tied to a specific living entity on the The planet of Moontides, coming into existence when the entity is born. As the entity's life progresses, glowing etchings appear on their pane, keeping a detailed record of everything that they are doing and that happens to them. The surface of them also behaves similar to a touchscreen, allowing even their fixed A4 size to still record entire life stories of people. You just have to scroll by touch to see all the pages. If you are looking for a specific person or event in a person's life, you only have to think it and the location of the glass pane in question will pop into your head, so long as your are in Mortuary's house or in the vault.
Picking up the pane allows you to immediately pan to the section of a person's life you are interested in simply by thinking of it. This particular magic works even if the pane is removed from Mortuary's vault or even his home plane. Mortuary himself has the power to summon any person's pane into his hand simply by thought, a power granted to him as the Lord and Scribe of Death, and this power is shared by all of his current apprentices working on reaping souls. Vega Faden , however, has been stripped of this access after it was assigned to follow the Glassless Child.
The Glassless Child is the first and only ever entity known to be born without a corresponding glass pane. At least neither Mortuary nor Vega Faden (while it was still an apprentice) could summon Sabah's pane anywhere, and Mortuary even arranged a recall of all his apprentices to manually search through the generations of glass panes of the vault to try and discover it. Nowadays, only a few apprentices and Mortuary himself stays behind in the vault quite often, working in shifts in the vault to try and find Sabah's pane. Most have given up, with Vega Faden permanently assigned to accompany Sabah around to learn more about her and potentially discover the cause of her missing pane.

Current Holder

Mortuary