Netherese Spellshard

Wondrous item, artifact

This crystalline shard, approximately the size of a dagger, contains the essence of a single Netherese spell preserved from before the fall of the empire. When found, the DM chooses one spell from any class spell list of 9th level or lower. While holding the shard, you can cast this spell once per day without using a spell slot or providing material components. The spell is cast at its lowest level.

A spellcaster who studies the shard for 48 hours can attempt to learn the spell it contains. The character must succeed on an Intelligence (Arcana) check with a DC of 10 + twice the spell's level. On a success, the character adds the spell to their spellbook, spell list, or spells known if it's of a level they can cast. Once a character learns a spell from the shard, it becomes a crystal with seemingly no magical properties for the next hundred years.