Wall of Thorns

The wall of thorns spell creates a barrier of very tough, pliable green tangled brush bearing needle-sharp thorns as long as a person's finger. 

Any creature breaking through (or merely impacting upon) the wall of thorns takes 8 hit points of damage plus an additional amount of hit points equal to the creature's armor class, i.e. 10 or fewer additional hit points of damage, with negative armor classes subtracting from the base 8 hit points of damage. 

Any creature within the area of effect of the spell when it is cast is considered to have impacted on the wall of thorns and in addition must break through to gain movement space. The damage is based on each 1" thickness of the barrier. 

If the wall of thorns is chopped at, it will take at least 4 turns to cut a path through a 1" thickness. Normal fire will not harm the barrier, but magical fires will burn away the barrier in 2 turns with the effect of creating a wall of fire while doing so. (See wall of fire spell.) 

The nearest edge of the wall of thorns appears up to 8" distant from the druid, as he or she desires. The spell lasts for 1 turn for each level of experience of the druid casting it, and covers an area of ten cubic inches per level of the caster in whatever form the caster desires. 

Thus a 14th level druid could create a wall of thorns 7" long by 2" high (or deep) by 1" deep (or high), a 1" high by 1" wide by 14" long wall to block a dungeon passage, or any other sort of shape that suited his or her needs.

Dexterity bonus to armor class is NOT considered in this case. If a wall of fire results from the burning of the thorns, the side towards the druid will be the non-harmful one.