Glyph Slabs

Glyph Slabs, or Glyphs for short, were stone tablets used by the Durangal Empire during the peak of their power.
Though unused ones are incredibly rare, they were used for note taking or messages to be delivered quickly to others by messengers who couldn't read them. More often than not they were used by the Ruler Cast to deliver orders to the front, or to receive updates of the progress of conflicts.
Activation of a new Glyph allowed the user of up to 100 words to be spoken to the stone, which would highlight on the stone itself, and then when the user was content with the format and context of the message, it would burn the message into the stone itself making an engraving that would take weeks to do by hand.
Glyphs were relatively inexpensive to produce. Usually the most time consuming aspect was the cutting of the stone slabs, the magical spells cast upon them to function was much easier to do in bulk.
Sometimes Glyphs would have extra spells places upon them by geomancers for specialized uses.
A couple of examples listed here:

• Breaking upon a number of readings
• Shattering after a certain amount of time passed
• Not burning the letters into the stone until after a special word or phrase was uttered
• A recording of the voice that originally sent the message as well

Most of the Glyph Slabs were also given a curse that would permanently blind any non-dwarf who attempted to read them, though it seems that most of the time the curses have since worn off. 
Unused Glyph Slabs are actually worth a lot of money now to the right person. Since they seem to be able to turn any word spoken into the Durangal language, which is famously incredibly hard to decipher.  
Only three unused Glyph Slabs have ever been found.

"I can't read any of these damn things, and they break so easily!" - Unknown Tomb Raider

Item type

Magical

Manufacturer

Durangal Empire

Owning Organization

Durangal Empire

Rarity

Though more and more rare as time passes, some of these slabs can be found in old ruins deep underground.