Arcane Storage

You store a spell of 4th level or lower for later use, also allowing other creatures to cast it. The spell is stored within a small sapphire. Any creature who possesses the gem can cast the spell. The spell’s spellcasting ability and save DC, if any, are the same as the initial caster’s. The gem then crumbles to powder.

The original caster may also detonate the spell inside the gem at any time. If the spell requires sight, then it targets whatever the user holding it sees first. If not being held or in possession of anyone, then the gem will explode for 3d6 force damage.