Draw Power

This spell allows the caster to tap in, and draw spell power from an existing bound focus. The caster can either draw in spell levels to replenish their expended  spell slots, or draw enough spell power to be able to cast their next spell without expending a spell slot. A caster can only hold an amount of extra magic equal to 1/2 their caster level rounded up. Once they cast their next spell all the extra energy will be used regardless of what level the spell they cast was. The caster is considered to be concentrating on a spell as long as they are holding this extra energy, and if their concentration is broken by anything other than casting a spell, the energy is lost. 

The caster can also cast a spell which has a duration other than instantaneous, and an area of effect that would be large enough to include the bound magical focus point. Then as a bonus action use Draw Power to link the spell to the focus. The Focus will continue to power this linked spell by spending an equal amount of spell levels equal to the level of the spell every time the duration ends to re-cast the spell. This will continue until the bound focus runs out of stored spell levels, or the spell is ended by the caster, or it is dispelled. If the spell requires concentration it does not use the casters concentration while it is being powered by the bound focus. If the spell requires material components to renew the casting, it does not need them. If the spell needs to be guided like a blade or other attack spell, or summoned creature then there needs to be a caster inside the area of the bound focus to control it, or it will take no action. Finally once the spell is passed to the bound focus, it becomes the effective caster of the spell, and all range and other modifiers based on how far the effect is from the caster use the bound focus as the starting point. If any of the targets get to make a saving throw against a spell being maintained by the focus, the saving throw DC for the original spell caster is used.