Exploding Spheres
Mechanical Trap (Level 5–10, Dangerous)
Designed to protect valuable treasure hoards, this trap consists of several highly polished metal spheres concealed within an ornate metal cylinder. Both the spheres and their container appear to be valuable treasures in their own right, tempting unsuspecting adventurers to investigate.
Each sphere is perfectly smooth and coated in Oil of Slipperiness, making them extraordinarily difficult to grasp or control.
Trigger. When a creature opens the polished metal cylinder containing the spheres, it must succeed on a DC 18 Dexterity check to prevent the slippery spheres from spilling out.
Effect. On a failed check, the spheres tumble to the ground and roll in different directions before violently exploding, spraying flammable liquid that ignites in a 30-foot radius around the cylinder.
Each creature within the affected area must make a DC 16 Dexterity saving throw, taking 21 (6d6) Fire damage on a failed save, or half as much damage on a successful one.
Detection and Countermeasures. A successful DC 18 Wisdom (Perception) check reveals a subtle mechanical release mechanism within the cylinder. A creature can attempt a DC 18 Dexterity (Sleight of Hand) check to open the container while preventing the spheres from spilling out.