Concealment: Jacket
Four spikes pointing out from a core is such a way that at least one point points up when scattered on the ground. They are often poisoned - but gets no free poison.
A packet of caltrops is about two dozen and will cover five one-meter squares and can be spread as a 3-shot action. They need darkness or some concealment, such as grass, to work well.
Caltrops is a Traps, and uses the normal rules for discovering traps. An Intrusion or Perception roll against a difficulty of your FixIt or Intrusion will discover it. Specifically looking for traps gives a +3 bonus. Caltrops whose presence is known are less dangerous the difficulty is only 5 in such cases. Running through a field of caltrops is dangerous even if their presence is known it disallows the use of Intrusion, forcing the runner to rely on Perception alone.
Caltrops cause one Wound Point for each point of negative Outcome. Typical shoes reduce damage by one, while heavy boots reduce damage by three and metal-soled boots reduce it by five. If any damage is inflicted, the victim stops dead in his tracks to recover his balance and remove the caltrop. A normal-sized caltrop will simply be crushed if the victim has Toughness of 10 or higher, tough oversize caltrops can be made to stop horses, giants and even tanks.