Bristle

(Spell Compendium, page 40, DnD 3.5)

Transmutation

Level: ; Sorcerer/Wizard Variant 2
Components: V, S
Casting Time: 1 Standard Action
Range: Touch
Target: Suit of armor touched
Duration: 1 round/level (D)
Saving Throw: None
Spell Resistance: No

With a word and the sudden opening of your hand you complete the spell. Touching a suit of armor instantly causes the armor to sprout long, deadly-looking spines.

The bristle spell temporarily enhances one suit of armor, causing it to grow long hard spikes that stick out in all directions. This spell does not work on clothing other than armor, but it does function with armor that already has spikes built in. The spikes are flexible enough not to hamper the creature wearing the armor. Each round, the first time the armor wearer attacks a target in melee, the spikes strike out as well, growing in length and hardness. The spikes have an attack bonus equal to your caster level and deal 2d6 points of damage. Your Strength modifier does not apply to this damage.