A carpet of tiny steel spheres rolls towards you.
Warden Jack Swarm CR 4
Warden jack swarms have two modes of attack: as moving caltrops, or as rolling marbles. They set themselves up for combat by rolling into the path of their opponents and extending their spikes.
During Combat Once combat begins, most of them roll around continually, extending their spikes and attempting to wound an opponent. Some remain in spheroid form in order to get under the feet of a foe and bring it to the ground. Extending or retracting spikes is a free action for the warden jack swarm.
Str 4, Dex 14, Con —, Int —, Wis 11, Cha 1
Base Atk +5; CMB —; CMD —
Wounding Spikes (Ex)
Any living creature hit by a warden jack swarm when its spikes are extended also takes 1 point of bleed damage.
Organization solitary, spill (2-5 swarms), or disaster (6-11 swarms)
Warden jacks are miniscule metal objects in the shape of a ball covered in sharp spikes. These things are able to move on their own by retracting their spikes, and rolling along the ground. They are commonly used as guardians by wizards and nobles who fear the intrusion of thieves. Warden jacks never attack their creator and can be programmed to avoid specific individuals or types of individuals, or to attack only specific types of individuals, or attack only under specific conditions as specified by the creator.
These constructs are capable of guarding an entire floor or area, but are unable to climb up stairs and are stopped by closed doors or other impassable objects that they cannot fit through. They can, however, fall down stairs or navigate even the steepest of slopes.
Warden jacks resemble caltrops somewhat, and typically range from 1-3 inches in diameter.
Warden Jack Construction
Individual warden jacks are formed from hardened steel and molded into their spherical shape. The steel used must be of high quality and cost at least 1,000 gp.
CL 8th; Price 8,000 gp
Warden Jack Swarm from the Tome of Horrors Complete, Copyright 2011, Necromancer Games, Inc., published and distributed by Frog God Games; Author Scott Greene.