Inaccurate?

Bloodbriars

(Lost Empires of Faerun)

Evocation
Level: Druid 4, Sorcerer 4, Wizard 4,
Components: V, S, M,
Casting Time: 1 standard action
Range: Medium (100 ft. + 10 ft./level)
Target: 1 creature
Duration: 1 minute/level (D)
Saving Throw: Will negates
Spell Resistance: Yes

This spell, commonly used by the armathors of Myth Drannor in the apprehension of criminals, snares the target in a tangle of invisible, razor-sharp briars of mystical energy.
The affected creature suffers no ill effects as long as it does not attempt to move, attack, cast a spell with material or somatic components, or perform any other action that requires movement.
During any round in which the target moves in any fashion, however, it takes 1d8 points of damage (no save).
Damage from the spell disrupts spellcasting; a subject that attempts to cast a spell with a material or somatic component must make a Concentration check (DC 10 + spell level + damage dealt) or lose the spell.
Material Component: A drop of blood.