Petal Storm (M3, W3)

Level12

You conjure a 5-foot storm of leaves and flower petals from another world, magically honing their edges to be sharp as razors. You create the storm in a square within range and can take a move action to move it up to 30 feet in any direction. If the storm enters (or is created in) a square containing a creature, the petal storm can’t move any farther that round and deals @[3d6 slashing damage][roll 3d6 as damage for 'Petal Storm'] to that creature (Reflex negates). If you don’t move the storm, it remains where it is.

Any creature that shares its space with the storm has concealment (attacks have a 20% miss chance).