Wall of Thorns

The wall of thorns spell creates a barrier of very tough, pliable, tangled brush bearing needle-sharp thorns as long as a person's finger. Any creature breaking through (or crashing into) the wall of thorns suffers 8 points of damage, plus an additional amount of damage equal to the creature's AC. Negative ACs subtract from the base 8 points of damage, but no adjustment is made for Dexterity. Any creature within the area of effect of the spell when it is cast crashes into the wall of thorns, and must break through to move. The damage is based on each 10-foot thickness of the barrier.
If the wall of thorns is chopped at, it takes at least four turns to cut a path through a 10-foot thickness. Normal fire cannot harm the barrier, but magical fires burn away the barrier in two turns, creating a wall of fire effect while doing so (see Wall of Fire). In this case, the cool side of the wall is that closest to the caster of the thorn wall.
The nearest edge of the wall of thorns appears up to 80 yards distant from the caster, as he desires. The spell lasts for one turn for each level of experience of the caster, covers one 10-foot cube per level of the caster in whatever shape the caster desires. Thus a 14th-level caster could create a wall of thorns up to 70 feet long by 20 feet high (or deep) by 10 feet deep (or high), a 10-foot-high by 10-foot-wide by 140-foot-long wall to block a dungeon passage, or any other sort of shape that suited his needs. The caster can also create a wall of five-foot thickness, which inflicts half damage but can be doubled in one of the other dimensions.
Note that those with the ability to pass through overgrown areas are not hindered by this barrier. The caster can dismiss the barrier on command.

Sphere: Plant, Creation, Summoning
(Conjuration/Summoning)
Level: 6

Range: 80 yards
Components: V, S
Duration: 1 turn/level
Casting Time: 9
Area of Effect: One 10-foot cube/level
Saving Throw: None