Arcane Band

Five glowing gems filled with arcane power are embedded into the band. As a bonus action, the wearer can use the power within the gems to create a spell slot equal to the number of gems expended. The spell slot can be created of a higher level than the spellcaster currently has access to, but an only be used to cast spells the caster knows. If a caster exceeds their maximum spell slots for a level, the additional spell slots dissipate after 1d4 hours. 

After all five gems have been drained of power the band becomes a mundane golden band.

Notes: Utility, Wristwear