Spike Stones

Rocky ground, stone floors, and similar surfaces shape themselves into long, sharp points that blend into the background. Spike stones impede progress through an area and deal damage. Any creature moving on foot into or through the spell's area moves at half speed. In addition, each creature moving through the area takes 1d8 points of piercing damage for each 5 feet of movement through the spiked area. Any creature that takes damage from this spell must also succeed at a Reflex save to avoid injuries to its feet and legs. A failed save causes the creature's speed to be reduced to half normal for 1 minute.