As two actions, you remove all the oxygen in a sphere centered on a point within 20 meters. Each creature in the sphere must make a Fortitude saving throw. This spell has no effect on creatures that do not breathe.
On a failed save, a creature loses 3d6 health and cannot speak or use breath weapons until the end of its next turn as a visible line of swirling air leaves the creature’s mouth.
On a successful save, a creature takes half as much damage.
You can increase the health lost by 2d6 for each additional mana expended.