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Building Great Traps

by Mike on 5 December 2011

Good traps are hard to find. Using the rules as written, you might expend a monsters-worth of experience from your encounter experience budget and have the whole party avoid the trap completely. Today we're going to look at a few ideas that might make your traps more effective. While you don't want to use these ideas all the time, a few of them placed at the right time can make your traps more effective and your encounters faster and more dangerous than ever before.

Keep your traps simple

To begin, here are a few tips to keep your traps simple and effective.

Use static damage expressions instead of rolling dice. A flamespitting skull that does 15 damage on a hit is easier to keep track of than one that does 2d8+6 fire.

When it makes sense, have traps activate on a character's turn. Rolling a separate initiative for your traps slows down the game. Further, a trap that activates at the beginning of a character's turn scales with the number of characters in its range. A poison dart pillar trap will hit six PCs just as easily as three.

Use skill checks to disable instead of defenses and damage. It's easier to keep track of skill check successes than defenses and damage. When a character wants to blast or smash a trap, have them use the applicable skill instead of an attack power.

Traps should generally be immune to status effects. You can't mark them or slide them or daze them.

Good traps augment good monsters. Arcane traps might be tied to a wizard boss who battles the PCs. When the wizard dies, the traps cease their attacks. This helps you keep a battle focused and fast without sacrificing threats against the PCs.

Location, location, location

Good traps need to be well placed. Too often it's easy for PCs to simply avoid a trap by avoiding an area. When you're designing a trap-heavy encounter, ensure you have placed your traps to make them effective against a group of PCs.

The advantages of artillery traps

Artillery traps have a lot of advantages over other traps. Location doesn't matter nearly as much for a trap that can shoot across the whole room. You can also place artillery traps in challenging locations, getting PCs to move all around a room and engage in some difficult feats of acrobatics to reach them.

1d8 random traps

Here are a few random traps you might add into your dungeon encounters. Each of these traps activates when a PC begins its turn within range of the trap. An adjacent PC can deactivate these traps with two successful standard action medium DC arcane, athletics, or thievery checks. A PC may instead use a minor action to recklessly deactivate the trap. This uses a hard DC and failure activates the trap, targeting the failing PC.

Flamespitting Skulls: range 10; level + 3 vs Reflex; Level + 8 fire damage damage.
Poison Gas: 5 poison damage, increases by 5 every round.
Lightning Runes: range 5; level + 3 vs fortitude; level + 8 lightning damage and the target is dazed until the beginning of its next turn.
Poison Dart Pillar: range 10; level + 3 vs Reflex; level + 8 poison damage and ongoing 5 poison damage per tier (save ends).
Light Beam: range 10; level + 3 vs Reflex; level + 8 radiant damage and the target is blinded until the beginning of its next turn.
Screaming Walls: level + 3 vs Will; level + 8 psychic damage and the target is -2 to defenses and vulnerable 5 to damage until the beginning of its next turn.
Evard's Tentacles: level + 3 vs Fort; level + 8 force damage and the tentacles slide the target 5 squares.
Prismatic Beam: level + 3 vs Reflex; level + 8 fire, radiant, necrotic, and lightning damage and the target is teleported 8 squares.