Ioun Stone of Reserve

See: Ioun Stone
When you take a Magic action to toss an Ioun Stone into the air, the stone orbits your head at a distance of 1d3 feet, conferring its benefit to you while doing so. You can have up to three Ioun Stones orbiting your head at the same time.
As a Utilize action, you can seize and stow any number of Ioun Stones orbiting your head. If your Attunement to an Ioun Stone ends while it's orbiting your head, the stone falls as though you had dropped it.
This vibrant purple prism stores spells cast into it, holding them until you use them. The stone can store up to 4 levels of spells at a time. When found, it contains levels of stored spells chosen by the DM.
Any creature can cast a spell of level 1 through 4 into the stone by touching it as the spell is cast. The spell has no effect, other than to be stored in the stone. If the stone can't hold the spell, the spell is expended without effect. The level of the slot used to cast the spell determines how much space it uses.
While this stone orbits your head, you can cast any spell stored in it. The spell uses the slot level, spell save DC, spell attack bonus, and spellcasting ability of the original caster but is otherwise treated as if you cast the spell. The spell cast from the stone is no longer stored in it, freeing up space.