Obsidian Flow

You convert a thin layer of the ground to molten glass that cools quickly. Creatures in the area take 1d6 points of fire damage per two caster levels (maximum of 10d6) and become entangled until they make a successful Strength, Athletics or Mobility check (the DC equals the spell's saving throw DC). Any creature within the area that makes a successful Reflex save takes half damage and is not entangled. The ground is covered with slippery expanses and sharp shards of obsidian. The area of effect is difficult terrain and creatures inside this area take a –5 penalty on Mobility skill checks. A successful DC 15 Mobility check is required to charge across the area. A creature that falls prone in the area takes 1d6 points of damage from sharp obsidian.