Inaccurate?

Undulant Innards

(Lords of Madness)

Transmutation
Level: Sorcerer 3, Wizard 3,
Components: V, S,
Casting Time: 1 standard action
Range: Close (25 ft. + 5 ft./2 levels)
Target: One creature
Duration: 1 round/level
Saving Throw: None
Spell Resistance: No

This spell causes a powerful transformation in the target creature.
Outwardly, the target doesn't appear any different.
On the inside, the creature's internal organs constantly seethe and slither about, and actively avoid being struck at by weapons.
For the duration of the spell, the target is immune to extra damage from critical hits and sneak attacks.
Additionally, the target takesminimum possible damage from falls and gains a +4 enhancement bonus on all saving throws against poison, disease, and paralysis.