uncommon air evocation 

Cast [R] verbal; Trigger You make a successful unarmed Strike against a flying creature.

Targets the creature you hit

Saving Throw Fortitude

You deny a flying creature the support of the air.

Critical Success The target is unaffected.Success The target descends 60 feet. If it hits a surface, it takes bludgeoning damage as if it had fallen.Failure As success; if the target hits a surface, it falls prone and can't Fly, levitate, or otherwise leave the ground for 1 minute.Critical Failure As failure, and the creature takes double damage from hitting a surface.

Heightened (+1) Increase the distance the creature must descend by 20 feet.

LOIL, page 225.