Not a particularly useful spell as the sprites can't perform one of the basic functions of low-level summoned creatures soaking up retaliation damage. Still, the sprites high movement means the creatures can be used to divert incoming enemies from their path, giving you more time to soften them up with ranged attacks. To best use this strategy, turn movement shadows on, right click on the enemy stack to see the limits of their movement and then fly the sprites to either the furthest edge of the shadow or just beyond it - the former if the stack is close and will not be diverted if the sprites are not in attack range.