Gas Leak

A locked iron door is hidden in the back of the room.

Mechanical Trap

The room behind is filled with an odorless flammable gas. There is a flint and steel that strikes when the door is opened. A DC 14 Intelligence (Investigation) check detects a small piece of flint wedged between the door and the frame. With a DC 16 check, all the pieces of flint are detected (1d4 +1 pieces) When the door is opened, the flint sparks causing the gas to ignite. All targets within 30 feet take 6d6 fire damage, with a DC 14 Dexterity saving throw halving the damage. An open flame within 10′ of the door will also ignite the gas. A DC 22 Wisdom (Perception) check detects the ever-so-faint odor of gas. It requires a DC 16 Dexterity check with thieves’ tools to remove the flint without igniting the gas. Once the door is opened, the gas either ignites or dissipates. The gas fills the room back in 10 minutes after the door is closed.

Dry Hillside

A grassy hill leads up to a small manor.

Mechanical Trap

The hill is rigged to ignite. A DC 16 Wisdom (Perception) check detects that some of the grasses are artificial. A DC 14 Intelligence (Investigation) check reveals that the artificial grasses are made of wire that runs into the ground. A guard from the manor can trip the trap. When they do so, the wires spark, igniting the dry grass. All targets in the grass take 2d6 fire damage, with a DC 16 Dexterity saving throw halving the damage. On each target’s turn, a target that starts, ends, or enters the fire on their turn takes the above damage. The fire burns for 1d10+10 rounds before burning itself out. It requires 1d4+2 of the wires in the ground to be cut to disable the trap.

Water Filled Keep Next To A Cliff (Really)

A small tower keep is hear with a stout, wide and wooden door set into the side of the keep that is 15′ away from a steep cliff.

Mechanical Trap

The keep is filled with water. A DC 14 Wisdom (Perception) check reveals that the door is swollen with moisture. A DC 16 Intelligence (Investigation) check reveals that is is being soaked from the inside out. The door requires a DC 12 Dexterity check with thieves’ tools to open and a DC 10 Strength (Athletics) check to pull it open. When the door is pulled open, water comes rushing out. All targets in a 15′ cone must make a DC 16 Strength saving throw. On a failure, the target is swept over the cliff, where they fall and take 10d6 bludgeoning damage. A hole can be drilled into the door to drain the water. The door is 10′ high. If a hole is drilled 1 ft high or less, the water rushes out harmlessly when the door is opened. from 1 ft to 5 ft, the saving throw is at advantage, and higher than that has no effect on the saving throw.

Dunk Tank

A safe door is on the back wall of the otherwise empty closet.

Mechanical Trap

The safe door lever causes the floor to swing open to a pit of acid below. The safe can be cracked open with a successful DC 18 Intelligence (Investigation) check and a successful DC 16 Dexterity (Sleight of Hand) check. When this happens, an audible click is heard from inside the safe. Pulling the lever opens the door, but also opens the floor. The target must make a DC 14 Dexterity saving throw or fall into a pit of acid. The target takes 2d4 acid damage and then takes an additional 1d4 acid damage at the beginning of their turn. A DC 14 Intelligence (Investigation) check reveals the the edges of the floor are attached to mechanical levers. The floor can be secured with a DC 16 Dexterity check with thieves’ tools.

Contact Explosives

The wooden door has swollen up and is stuck in the doorway.

Mechanical Trap

Several barrels of highly volatile substances are stored behind the door. The door can be forced open with a DC 18 Strength (Athletics) check. It has AC 10 and 10 hp. Breaking or forcing the door causes the substances behind the door to explode with contact. All targets in a 15′ cone in front of the door take 3d6 fire and 3d6 bludgeoning damage, with a DC 16 Dexterity saving throw halving all damage. If the door is instead disassembled, the explosives behind it can be moved without harm.

Dumpster Fire

Several sealed wooden barrels are here.

Mechanical Trap

The barrels contain a substance that is packed in a gel-like substance that reacts violently with air. A DC 14 Intelligence (Investigation) check reveals that the barrels are old and no longer airtight. If a barrel is opened, the substance explodes immediately as the gel has evaporated long ago. All targets within 30′ take 6d6 fire damage, with a DC 16 Dexterity saving throw halving the damage. Only covering the top of the substance somehow before opening the barrel keeps it from exploding.

Underwater Gate

The floor has an opening that exposes a pool.

Mechanical Trap

There’s a chest at the bottom that closes a gate over the pool when opened. A DC 12 Wisdom (Perception) check detects a chest 10′ down under water. The chest requires a DC 12 Dexterity check with thieves’ tools to open. A DC 14 Intelligence (Investigation) check reveals a thin filament that runs from the chest to the underside of the floor, connected to a sliding iron grate. This filament can be undone from the grate with a DC 16 Dexterity check with thieves’ tools. Cutting it, failing the check or opening the chest without disarming it causes the grate to slide closed, even with the waterline. Targets in the pool are trapped underwater. Opening the grate requires a DC 16 Dexterity check with thieves’ tools from the topside, or a DC 18 Strength (Athletics) check to force it open. Forcing it open from underwater makes the check at disadvantage.

Shooting Stairs

A set of stairs heads upwards.

Mechanical Trap

Each stair is edged with a sharp metal on its edge; these fire out when triggered. A DC 14 Intelligence (Investigation) check reveals that the sharp metal guards on each stair are detachable. When the middle stair is stepped on, each guard is launched outwards. All targets on the stairs, or in a 10′ cone in front of the stairs suffer a +8 ranged melee attack for 3d6 piercing and slashing damage. If the middle stair guard is removed via a successful DC 16 Dexterity check with thieves’ tools, the trap is disabled. Failure sets off the trap.

Collapsing Wall

A very narrow corridor runs next to the outside wall of the tower.

Mechanical Trap

The outside wall can give way. A DC 14 Intelligence (Investigation) check reveals that the outside wall of the corridor is very compromised and could collapse. If a target goes down the corridor, which is a very tight fit, the outer wall gives way, taking some of the floor with it. The target must make a DC 16 Dexterity saving throw of fall, taking 6d6 falling damage. If the target is careful, they can traverse the corridor by making a DC 12 Dexterity (Acrobatics) check for each movement. On a failure, the wall still collapses, but the target gains advantage on the saving throw.

Double Pit

The wooden floor is uneven here.

Mechanical Trap

There’s a pit in the floor, with another pit below it. A DC 14 Wisdom (Perception) check detects a 10’x10′ outline on the floor that is a trap door. Stepping on this area causes the target to make a DC 14 Dexterity saving throw, or fall into a 20′ pit, taking 2d6 bludgeoning damage. Additionally, the floor of the pit is false, and the target continues to fall an extra 100 feet, taking an additional 10d6 bludgeoning damage. If the pit is opened, the target sees some gold pieces on the floor or the pit. A target that applies 50 pounds or more of weight to the pit floor causes it to collapse. The target must make a DC 18 Dexterity saving throw at disadvantage or fall the 100 feet as above. Once in the pit, it requires a DC 16 Strength (Athletics) check to climb the wall. While the false floor can’t be disarmed, as long as the 50 lbs of weight isn’t applied to the floor, it won’t collapse.