A squirming and squeaky mass of rats with rotting flesh, torn and matted fur, and reddish blazing eyes moves toward you. Their semi-translucent skin shows discolored bones and muscle.
AC 15, touch 14, flat-footed 13 (+2 Dex, +1 natural, +2 size)
Str 6, Dex 15, Con --, Int 2, Wis 12, Cha 14
A shadow rat swarm can, as a standard action, assume an incorporeal form for up to 1 hour per day. In this form, the swarm loses its natural AC bonus but gains a +2 deflection bonus to AC. While in this form, the shadow rat swarm is AC 16 (+2 deflection, +2 Dex, +2 size), touch 15, flat-footed 13. The shadow rat swarm can still swarm attack corporeal opponents while in its incorporeal form, but its attack only inflicts Strength damage and cannot distract foes or cause physical damage. The shadow rat swarm gains the incorporeal subtype while using this ability.
A shadow rat swarm deals Strength damage to living foes over which it swarms. A creature reduced to 0 Strength cannot move but does not die--at least, not until the swarm's physical damage takes its toll.