gem of vortex captivity
Either max scarcity item or artifact. Absorbs adjacent vortexes, possibly capped at a certain limit (3-5?), after which there is a cooldown. The vortex can be released in two ways: as a companion, which doesn't create any cooldown, or as a missile (like farflung fireball) which does create a long cooldown and prohibits releasing or capturing until it does.