Nachazor Tablet
Wondrous item, artifact (requires attunement) Market Price: 100,000 gp
Legend of the Nachazor Tablet. There once was a type of celestial called a “Watcher” that dwelt among the human race since the early days of creation. The Watchers had sworn an oath not to interfere with the mortal world, but found themselves unable to stay true to this oath. A conclave of 12 Watchers meddled in human affairs, hoping to gift the young mortal race with knowledge and weapons to arm itself against the machinations of the demonic forces that sought to corrupt them. However, no sooner had the Watchers gifted them with these powers than the humans turned their new weapons on one another, and the world spiraled into chaos and bloodshed, eventually ending in the Great Flood that wiped out most of humanity.
As a result of breaking their oath, the Watchers were banished from the Heavenly Realm, and each of the 12 withdrew to remote corners of the universe in an attempt to repent for their actions which they came to realize caused more harm than good.
However, before the Watchers retreated into isolation, they created the Nachazor Tablet as a means for the human race to contact them if they were ever in great need. The eldest of the Watchers gifted this tablet to Noah for safekeeping.
A Fragmented Legend. On his deathbed, fearing what could happen if the tablet fell into the wrong hands, Noah broke the tablet in two, and entrusted the two halves to his sons Shem and Japheth, instructing them to hide the stones from one another and thereby seal away the influence of the Watchers forever.
Properties of a Nachazor Fragment. Even in its fractured state, each half of the Nachazor Tablet is considered a Rare magic item that requires attunement. A Nachazor Fragment can be used as a spellcasting focus and grants a +1 bonus to spell attack rolls. Additionally, you know the message cantrip while holding the Nachazor Fragment.
Reuniting the Tablet. If the two halves of the Nachazor Tablet are reunited and the Mend spell is cast on them, they stitch themselves back together. Once reunited in this way, a creature wielding the Nachazor Tablet can speak the true name of one of the 12 Watchers to activate it. Once activated, the tablet can cast the sending spell at will, targeting the Watcher whose true name was most recently spoken by the wielder.
Source attribution and license
Silk Road's Guide to Seafaring, printed pages 186.