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Traps in a Bottle

by Jae
traps in a bottle

Traps come in many forms. There’s mechanical traps, magical traps, puzzles, simple and complex. However, one of the major issue many players face is that traps are not something they can usually carry around or set themselves.

Outside of the simplest traps, players really only have a few options when it comes to getting the drop on their enemies. In an attempt to solve this problem, we’re proposing a few homebrew solutions that can easily fit into most games. Today we’re looking at traps in a bottle.

The Concept of Traps in a Bottle

These traps are spells taken from the 5e SRD that have AOE effects, such as Black Tentacles. Instead of the spell being an immediate effect, we instead have its effect bottled as a magical oil. The oil, when applied over a 5ft surface, creates a magical contact trap that will persist for 24 hours or until triggered. In the example of Black Tentacles, the effect would trigger when the oil is stepped into, upon which a smaller version of the spell goes off, effecting that 5ft space.

These traps solve a lot of problems for roguish players who want to use the element of surprise more effectively at higher levels. A trap is now something they can carry with them and apply in certain situations to many different effects.

tentacle trap

Balance and Mechanics

For these oil traps, there is all sorts of different ways you can adjust them for your game. If you’re not letting your players craft them, then balance simply relies on availability and cost. In the event that players can make them, cost of components and time required to make a magical item are how you can restrict their use in addition to their availability in shops.

When it comes to item rarity, that’s a call the DM needs to make. But it becomes unfeasible to make rare magical items as one shot concoctions based on standard magic item creation rules, so use your best judgement when applying these restrictions in your game.

For any of these items, it’s important to limit the use it. The effect should almost always be slightly less potent than the spell. Concentration spells that are turned into traps lose that requirement, but instead have their duration or area of effect decreased. Going back to our Black Tentacles example, the area of effect is reduced down to a single 5ft square instead of its full range. This makes the trap more focused and purposeful while also restricting its power and potential misuse.

Reduced spell

Use and Triggering

Oils from traps in a bottle should always take time to apply properly. Typically 5-10 minutes should be needed to ensure the oil is spread properly and set. This further reigns in potential for people to misuse or attempt to make game breaking scenarios.

Triggering the traps is always from a creature stepping into or disturbing the oil on the trapped surface. Complex triggering is not something that’s required for these and allows for plausible use by non-caster classes.

Additionally, once set the trap lasts for 24 hours or until triggered. The duration of the effect once triggered is based on the spell itself, but like mentioned above should be less than the length of the effect from the cast spell.

Applying oil


How you handle trap detection is something that comes down to personal preference for the DM in many cases. Often you’ll try to prevent your players from shouting “I CHECK FOR TRAPS!” every time they enter a room. So to this end we recommend using passive perception to detect any slick or discolored surface or follow rules for detecting magic. The traps are magical in nature and would give off a magical aura appropriate to the spell they are based on. The traps can be dispelled magically or the oil can set off remotely by disturbing it after it dries.

Detecting surface

So Much Potential for New Traps

These new options for traps in a bottle from the base spell list present a whole range of different applications. In our research for this article we’ve already identified multiple spells that this makes sense for. We encourage you to get creative with this too. Create some special cases, common variants, or let your players ask for the types of traps they’d like.

By making traps more accessible to the players you allow them to broaden their play styles and give them new options to experiment with. You might just get some fun new levels of strategy out of your group.

If you use these trap ideas in your game, let us know. We’d love to hear from you and would be excited to find out how your group used them!

As always, Happy DMing!

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