Wondrous item - Legendary
A small shard of sjelestein, no larger than a gold coin, has 7 charges. The gem emits dim purple light in a 5-foot radius. While holding the gem, you can use an action to spend 1 of its charges to cast an enchantment spell of 3rd level or lower. You do not have to know the spell or have it prepared to use this benefit, but to use a spell you do not know or have prepared, you must first succeed on an Intelligence (Arcana) check with a DC equal to 10 + the spell’s level (0 for cantrips). Otherwise, the spell fails. You can expend additional charges to cast enchantment spells of higher levels, expending one charge per level above 4th. The gem regains 1d6 + 1 charges daily at dawn. If you expend the gem’s last charge, the gem stops glowing and it loses its magic.
Sjelestein Madness.
Each time a wielder expends a charge of the sjelestein, it must make a Wisdom saving throw with a DC equal to 10 + the level of the spell cast from it (0 for cantrips). On a failed saving throw, the wielder gains one form of indefinite madness. This madness can only be removed by a healing spell of 6th level or higher, such as the heal spell.