Fleshwarping Swarm

Conjuration (Summoning)
Level: Artificer * 3, Sorcerer */Wizard * 3, Summoner * 3, Warlock * 3
Components: V, S, M/DF (a square of red cloth)
Casting Time: 1 round
Range: close (25 ft. + 5 ft./2 levels)
Effect: one swarm of bats, rats, or spiders
Duration: concentration + 2 rounds and 1 hour/level (see text)
Saving Throw: None
Spell Resistance: no
  This spell functions as summon swarm, except that living and undead creatures that fail their saving throw against the swarm's distraction find that their limbs twist and spasm, as their bodies become susceptible to transmutations. Such creatures take a -4 penalty to Dexterity and on saving throws against transmutation effects for 1 hour per Caster Level.