Been thinking a lot about the Exploration pillar in 5th Edition lately—and traps in particular. When you are adding combat scenarios to your game, it’s easy to understand why they’re there: bandits want to steal from the characters, demons want to spread chaos, and for beasts, they just want to defend their lairs. Similarly, it’s easy to understand the motivation behind roleplaying and social encounters: the spy is hoping the character will let something slip, the merchant wants to sell their product and will share some gossip to make a connection, the bully is trying to get the character to back down. For both combat and social encounters, it’s easy to see the purpose for adding them to your game to advance your shared narrative. Want to point your characters toward the bandit’s forest hideaway? Then a bandit ambush on the road is a quick way to introduce your next adventure.

Exploration however can be a lot harder to get a handle on. Why is that cool piece of terrain or lore even in your adventure other than the fact that you need something there? This leads exploration to often be overlooked and for traps, the most common representation of exploration, to be placed without thought, little more than filler for your adventure design space. It doesn’t have to be that way. Traps have purpose just as your NPCs have motivations. Whether it’s a simple alarm to alert defenders of approaching enemies or a pit with the intent to take captives, consider the purpose of the trap and how it ties into your adventure.

Setup: The Brokentooth Goblins

Goblins have been raiding local farms, stealing livestock, and burning crops. The farmers have had enough. Pooling what little coin they have, they hire a group of adventurers and point them toward the Jagged Hills where the tribe is known to lair. The goblins and their chief know that the locals know approximately where the goblin lair is and expect them to eventually send someone after them. Chief Agnok is forward-thinking and orders his goblins to start preparing traps for their expected visitors. They start by defending the entrance to their lair knowing that if they can keep the adventurers contained, they will be easier to defeat. The lair has a Y-intersection 15-feet past the cave entrance with two tunnels leading deeper into the tribe’s home.

Trap Design

Time to ask some questions in order to get just what we want from our trap.

As the GM, do I want the trap to be the entire encounter the players interact with, to augment some other part of an encounter, or is it a quick, simple trap?

For this one, we want an encounter where overzealous adventurers are drawn into the goblin’s lair just far enough to where once an ambush is sprung they have trouble withdrawing. Mechanically, the trap should augment another encounter. We don’t want to assume the group is going to have anyone proficient in thieves’ tools, so let’s build in some way to avoid or nullify the trap at least partially with creative thinking.

What did the goblins hope to accomplish by setting this trap?

With this trap, the goblins are hoping to sound an alarm, to kill or wound intruders, and to potentially take some captives.

What are the goblins capabilities in crafting the trap?

The Brokentooth Tribe doesn’t have access to any magic, but they are darn sneaky. In order to build their trap, the goblins have significant manpower and can use things found in the hills (rocks, wood, and maybe hides) and things they have stolen from the farmers (animals, farming tools, oil, and the like).

Do the goblins need to get past the trap, and if so how?

Since the trap is going to block their entrance, we are going to need to build in a way for the goblins to get through when they are not in combat.

So here’s what the goblins do.

Caging Oily Pit Trap

Simple trap (level 1–4, dangerous)

At the entrance to the tunnel, there is a portcullis made of timber that rises into the rock. The goblins keep it open, and there does not appear to be any obvious way nearby to raise or lower it. A little farther along (10 feet) into the tunnel (5-feet before an intersection), the goblins have dug a 10-foot-square, 10-foot-deep pit. The pit is covered by a brown horse blanket stretched on sticks and further covered with dirt, so it looks like the rest of the floor. In the pit, the goblins have placed two barrels’ worth of oil and several cow bells (stolen from the farmers), hanging from the blanket.

Trigger. A creature that steps on the blanket falls into the pit.

Effect. The triggering creature must succeed on a DC 15 Dexterity saving throw or fall into the pit, taking 5 (1d10) bludgeoning damage and being covered in oil. When the cow bells alert the goblins on watch in each of the other two tunnels, one of them cuts a rope holding the portcullis aloft, causing it to slam down and seal off the entrance. Lifting the portcullis requires a successful DC 15 Strength check.

Secondary Effect. If the character that fell into the pit is alive, the goblins threaten to drop torches into the pit if the party doesn’t surrender. Any character in the pit when it is set on fire suffers 5 (1d10) fire damage for every round they are on fire. There is enough oil in the pit to burn for three rounds. Climbing out of the pit requires a successful DC 15 Strength (Athletics) check.

Countermeasures. A successful DC 15 Wisdom (Perception) check reveals the blanket. The portcullis can be jammed with logs or rocks found in the area, and the pit could be crossed with a log or similar item that is longer than 10-feet. Indeed, the goblins have taken doors from one of the barns they raided and placed one in each side tunnel, so they can cross the pit safely.