These are roiling globes of magical energy that travel across the battlefield. A Magical Vortex does not require a target – instead, it uses a round template which is placed on the battlefield, not touching the bases of any models, and with its central hole within the range given by the spell. Once placed, Magical Vortexes remain on the battlefield (unless they move off it).
Some Magical Vortexes move at the start of each turn, often by scattering. Should a Magical Vortex end such a move over a unit, move it by the smallest amount possible, in any direction, so that it can be placed on the battlefield, not touching the bases of any models.