Giant Rolling Boulder
Level 14 Minion Blaster
XP 250

When this trap is triggered, a huge rolling boulder is released and crashes through a false wall. It begins rolling down the hall, crushing everything in its path.

Trap: A trigger you define releases a distant boulder that begins rolling toward the trigger area, and it rolls until stopped.Perception     DC 23: A character near the distant false wall can determine that it is thin and that a large space is behind it.     DC 28: A character realizes that the trigger is in tension and that setting it off releases something.Initiative +2          Speed 8(consider altering this based on the length of the roll and the PCs’ speeds)TriggerThe trigger might be an enemy pulling on a lever, a character pressing the wrong button, or someone taking the gem from a statue’s eye. When the trap is triggered, roll initiative. On its initiative count, the boulder moves.AttackStandard Action or Immediate Interrupt      Area trample attack in squares entered by the boulder
Trample: Each turn, the boulder moves its speed and enters creatures’ spaces. This movement does not provoke opportunity attacks. The boulder can end its move in an occupied space. Creatures in the boulder’s space at the start of their turns have cover and can act normally. When the boulder enters a creature’s space, the boulder makes a trample attack. If a creature enters a square of the boulder’s space, the boulder makes a trample attack as a free action.Trample Attack: +17 vs. ReflexHit: 3d10 + 6 damage, and the target is knocked prone.Miss: Half damage.Countermeasures     Athletics DC 28: A character adjacent to the rolling boulder can stop it with a successful check. Making this attempt provokes a trample attack as an immediate interrupt, and the character’s Athletics check fails if the boulder’s trample attack hits.
     Thievery DC 23: A character adjacent to the trigger (or the location from where the trigger is activated) can delay the trigger with a successful check.
     Thievery DC 23: A character adjacent to the boulder before it begins to roll can disable the trap with a successful check. The character must have broken through the false wall first (AC 4, Fortitude 12, Reflex 4; hp 30).

Published in Dungeon Master's Guide 2, page(s) 69.