It's a Trap!

(Rule)
Description: Universal Rule

Each unit of Scrapling Trappers may place a Trap Counter:
• Right before the battle (during step 7 of the Deployment Phase Sequence), on a single Terrain Feature other than Open Terrain that the unit was deployed in or was in contact with at any point during its Vanguard move
• Once during each friendly Movement Phase, on a single Terrain Feature other than Open Terrain that the unit was in contact with during an Advance Move, March Move, or a Reform in this phase
If an enemy unit performs an Advance Move, March Move, Reform, Pivot, Charge Move, Failed Charge Move, Pursuit Move, Overrun Move, or Flee Move inside or into contact with a Terrain Feature with one or more Trap Counters, remove all Trap Counters in that particular Terrain Feature. Each model in the unit must take a Dangerous Terrain (1) Test. These tests are not considered to be caused by the Terrain Feature; any Dangerous Terrain Tests that would normally be caused by the Terrain Feature still need to be taken.