Thorn growth is a more powerful version of the barkskin spell. When this spell is cast, the priest's skin assumes the coloration and texture of wood and grows 1-inch-long thorns. For the duration of the spell, the priest has AC 3, inflicts an extra 1d3 points of damage with each unarmed attack (including grapples), and gains a bonus to her saving throws of +1 for every three levels of experience. This bonus does not apply to fire-based attacks.
While affected by this spell, the caster can be the source of a hail of thorns spell, which functions normally, although this ends the thorn growth spell immediately.
The material component is a blessed thorn, which is consumed in the casting.