One of the easiest ways to make your combat encounters more interesting and difficult inDungeons & Dragonsis to introduce environmental hazards. These are dangers, objects, and other elements that you can place on a battle map for your player characters and NPCs (non-player characters) to interact with.
The cardinal sin of battle map combat is placing the characters and their opponents in a blank room. Using environmental hazards, you will never commit this cardinal sin again, and your players will undoubtedly thank you for it.
10Water
The simplest and most obvious environmental hazard to put in any counter is water. Whether it’s a river, a lake, a handful of puddles, a waterfall, or something else, water offers a lot of different options that can change the landscape of your battlefields.
Creatures without swim speeds typically count water as difficult terrain which means it will cost them double their movement to get through water squares. However, a waterfall might offer partial or total cover from ranged attacks, and a river with a strong current might require an Athletics check to cross without being swept away.
Here’s a simple way to see the effectiveness of water: place a handful of ranged attackers on the far side of a river from your party.
The party’s melee characters will instantly find themselves in a conundrum.
If you feel like being especially devious, give the enemy ranged attackers cover in the form of trees or bushes as well.
9Pit Traps
Yet another classic environmental hazard is the simple pit trap. Opponents such as bandits, goblins, and kobolds are sure to make use of these kinds of devices when your party is fighting them on their home turf. Pit traps also have the surprise effect of turning a combat that seemed simple enough into a suddenly deadly affair.
Beyond that, including these hazards on your map can reward players who have put points in their perception score as a high enough passive perception mayreveal the trapbefore a character steps on it. Just remember that passive perception only applies within five feet of your character, so characters with a high passive will need to be moving across the battlefield to spot these dangers.
8Falling Net
Typically less effective than the pit trap but also less frequently expected is the falling net. This trap is best for harrying non-Strength based characters as it takes an Athletics check to escape one. However, the net can also be physically attacked with a slashing weapon or fire and dismantled that way. This alternative method of escape rewards thinking players.
While basic nets are easily overcome once encountered a couple of times, you may always up the ante by using steel nets that can’t be cut, magic nets that shock whoever is unlucky enough to get trapped in them, or razor-sharp nets that have been lined with sharp objects such as daggers.
7Elemental-Breathing Statue
Statues that breathe an elemental burst of energy are technically magical traps, which are a great tool to use on your party once they think they’ve got the hang of your run-of-the-mill environmental hazards. While this hazard is usually set off by a pressure plate that can be noticed with a high enough passive perception, it can also be revealed by a handy casting of detect magic.
In other words, this is yet another hazard that can lead to players celebrating their intelligent and cautious gameplay. Beyond being disabled with thieves tools like other traps, these statues can also be put to rest through a successful casting of dispel magic. All in all, they’re a great way for the magic half of your party to get in on recognizing and disabling hazards.
6Boiling Oil Or Acid
If you want to run a larger combat like the siege of a keep or castle, it would be remiss not to include the medieval terror of boiling oil or an acid-like equivalent. These can trigger like falling nets or you can simply let some of your enemies use their actions to pour buckets of the stuff on your unsuspecting party.
Once doused in one of these substances, a character will take recurring damage at the start of every one of their turns until they take an action to scrape the substance off. This gives players a difficult choice between losing most of their turn or braving the risk of taking more damage. Furthermore, smart play such as wading into a nearby river or well is yet another way to delight players.
5Poison Darts
When it comes to hazards, it’s just hard to beat the classics. Poison darts may be simple enough at first glance; however, there’s a lot of room to customize the exact poison your PCs might be afflicted with. Typical poison darts just deal additional poison damage, but you could have them inflict a condition such as poisoned, sleeping, or paralyzed instead.
There’s also the option to have a particularly potent poison do both! Chapter 8 of the Dungeon Master’s Guide has a good selection of poisons that have already been made for your ease of use.
4Rolling Sphere
This is a hazard that has an initiative of its own. That’s not just a joke; the boulder actually rolls for initiative if this hazard happens to be triggered. Player characters in the way of the boulder’s trajectory, when it takes its turn, will find themselves in a world of pain as it rolls right over their fragile bones.
There’s also the option to include some less-than-obvious trajectory changes for a rolling sphere if a particularly intelligent dungeon-dweller has preemptively created a sort of race track for the hazard. Ideas here include sections of wall that are hidden doors for the sphere to roll through, curved corners in a room to let it turn, and even methods of teleporting the boulder.
3Glyph Of Warding
Speaking of teleporting boulders, glyph of warding is the most likely means by which your evil henchmen can accomplish this feat. This is a third level spell with a casting time of one hour that inscribes an almost imperceptible glyph on an object or surface. Detecting the glyph requires an Investigation check against the spellcaster’s spell save DC (Difficulty Check).
Glyphs can be set in two modes. The explosive runes option makes the glyph into an elemental bomb that deals 5d8 damage when someone messes with it. However, the much more interesting option is to set the glyph with a spell. This option lets you store a spell of third level or lower in the glyph, which is cast when the glyph becomes triggered.
Great spells to put in a glyphinclude thunderwave, web, hypnotic pattern, fireball, hold person, and many, many more.
Concentration spells are a great choice in particular as they automatically last their entire duration and require no concentration from the original caster.
Also, you can upcast glyph of warding to store higher-level spells as well.
2Portcullis Or Wall
The old adage ‘never split the party’ exists for a reason. Many players adhere to this and prevent their dungeon master from singling them out and making each of them more vulnerable. That being said, there’s not much a party can do when a wall or portcullis drops from the ceiling between them and monsters attack the characters on both sides simultaneously.
This hazard forces players to think out of the box quickly to bring their party back together. A portcullis can be beaten throughmany different means of teleportation; however, a wall is much more tricky. This is a great opportunity for Strength-based characters in particular to shine, whether they’re trying to lift the wall or protect their more fragile party members.
1Lava
The Dungeon Master’s Guide tells us that a character submerged in lava takes 18d10 fire damage. That works out to an average of about 100 points of damage which is enough to nearly one shot even the highest level characters. For this reason alone, lava is easily the most dangerous environmental hazard you can put on a battle map.
Lava should be used sparingly, but it’s a great inclusion in any climactic boss battle or high-level adventure. Especially if you have fire-immune creatures that can grapple the characters and pull them directly into it. Yeah, that’s going to leave a mark.
