Crushing Sphere of Air

[Air] (Rare)
Level: 7
Casting Time: 1 action
Range: Close (25′ +5′ / 2 levels)
Area: 20′ radius circle
Duration: Concentration
Saving Throw: Reflex negates
Weave Resistance: No
  This weave creates a sphere of air that encompasses a target, similar to the weave harden air, and then collapses, dealing crushing damage to those trapped within. The target, or targets, of the weave take 1d4 points of damage per round. This damage is cumulative (i.e. 1d4 the first round 2d4 the second 3d4 the third, etc). If the target makes its reflex save, it manages to jump clear of the area and takes no damage. The sphere of air will act as a barrier to all physical objects, but not to the One Power or the True Power.
  +1 Casting level: For each additional casting level, the channeller may target one additional creature, as long as they are within the 20 ft. radius area of effect.
  +2 Casting Levels: By casting the weave two levels higher, the channeller can cause the sphere to collapse faster. This will raise the damage one step (1d4 to 1d6, 1d6 to 1d8, etc). Damage can be raised in this manner multiple times.
[UtDB]

Notes: