Spring-Arm Spike CR 4
A spring-arm spike is similar to a spring snare trap in that it incorporates a strong sapling bent into a taut arc. When a creature enters a square that contains the spring-arm spike’s trigger, the sapling snaps forward, driving a pointed spear into the target. The spring-arm spike makes a melee attack +15 (2d10+4/×3) against the target, which is also knocked prone unless it succeeds at a DC 20 Reflex save.
Note: This is a wilderness trap. Skilled survivalists and trappers are adept at fashioning effective, if simple, traps from humble materials. A wilderness trap has an associated terrain wherein the raw materials for the trap are commonplace. Within these associated terrains, the base cost of each trap is calculated in sp rather than gp. Wilderness traps always have a CR of 5 or lower.
When in a trap’s associated terrain, instead of paying one-third the item’s price in raw materials, the trap maker can attempt a Survival check against the normal Craft DC of the trap + 2 × the trap’s CR. If successful, the trap maker finds the necessary materials in the wild after 1d4 hours of foraging + 1 hour per CR of the trap. She can then attempt a Craft (traps) check, also at the normal Craft DC + 2 × the trap’s CR, to build the trap, which takes another 1d4 hours + 1 hour per CR of the trap. Traps built with such crude materials don’t last long without maintenance; they have a cumulative 20% chance to break for every day they go without being tightened and reset (which requires 10 minutes of work but no additional skill checks).
At the GM’s discretion, other non-magical mechanical traps may be considered to have associated terrains and use the wilderness trap construction rules.
PRG Ultimate Wilderness © 2017, Paizo Inc.; Authors: Alexander Augunas, John Bennett, Robert Brookes, John Compton, Dan Dillon, Steven T. Helt, Thurston Hillman, Eric Hindley, Mikko Kallio, Jason Keeley, Isabelle Lee, Jason Nelson, Stephen Radney-MacFarland, Alex Riggs, David N. Ross, David Schwartz, Mark Seifter, Jeffery Swank, and Linda Zayas-Palmer.