Tag Archives: hide

How to Run an Ambush So Sneaky Monsters Bring More Than Claw/Claw/Bite

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Dungeons & Dragons includes lots of sneaky creatures proficient in Stealth, from Abominable Yeti to Yeti. That alphabetical range somehow fails to make my point, but more than 500 creatures fit in between. The game includes creeping monsters who work as ambush predators like spiders (Stealth +7), crafty ambushers like goblins (Stealth +6), as well as potential jump scares from wights, and jumping oh-shit surprises from bulettes.

When these creatures get some chances to lie in wait or to sneak up for surprise, they show the traits that make them more interesting than a claw/claw/bite sequence. Combat scenes feel more varied. Plus the barbarian gets to show off Feral Instinct. However, I have almost never run sneaky monsters for surprise, and based on countless convention games virtually every other DM plays sneaky wrong too.

Part of the blame rests on the fifth edition rule for hiding before an attack. “Compare the Dexterity (Stealth) checks of anyone hiding with the passive Wisdom (Perception) score of each creature on the opposing side. Any character or monster that doesn’t notice a threat is surprised at the start of the encounter.” In the highly technical jargon of game design, this rule is rubbish.

The worst check among the hiders determines surprise, so with multiple foes and checks, the chance of success veers quickly toward impossible. Based on real life, you might suppose that ambushes often work. Based on the D&D rules, the word “ambush” describes a imaginary event that can never happen, at least for groups of sneaky monsters. (For a look at the reverse of this dynamic, see In D&D, Letting Everyone Roll Certain Checks Guarantees Success, So Why Bother Rolling?.)

To fix the rule so ambushers can surprise, skip the roll to hide. As a dungeon master, you can set the difficulty class to spot an ambush just as you set DCs for other checks. Then, compare each character’s passive Wisdom (Perception) score against the DC to determine if the character is surprised. This matches the procedure you might use for a trap.

As a technique for setting the DC to detect an ambush, just add 10 to the ambushers’ Stealth bonus, so hiding goblins with Stealth +6 require a DC 16 to spot. If the sneaky creature has advantage, add 5 to the DC. For disadvantage, subtract 5 from the DC. A group setting an ambush has the edge of planning, preparation, and familiarity with the location, so a DM focused on realism might allow advantage and enable many surprises, but not the kind players favor. More entertaining ambushes probably lead to a mix of surprised characters and characters who act immediately. Such situations reward characters with high perception.

This approach boosts sneaky monsters and perceptive characters, but it eliminates die rolls and the fun uncertainty that dice add. By choosing a DC, the DM essentially decides who becomes surprised, and it’s always the same, oblivious characters. The D&D designers favor passive perception because it avoids slowing the game for rolling Wisdom (Perception) checks. In dungeons that encourage players to look frequently for traps, passive checks can speed past a lot of rolls. But lurking monsters deserve a different procedure: Just have players roll a Wisdom (Perception) check before the likely roll for initiative. The characters who fail their check begin surprised.

In an ambush, initiative can start at one of two times:

  • When the monsters attack.
  • When one or more characters notice the potential ambush.

This second case leads to judgement calls from the DM, but can also lead to interesting scenes. How the realization plays depends on how the perceptive characters react to spotting the attackers.

If the ranger draws a sword and yells, “To Arms!” then initiative starts and the less perceptive players begin surprised. Meanwhile, the monsters are already aware of their foes, so they start without surprise.

If the ranger plays it cool and tries to alert the party, then the scene turns on whether the ambushers happen to attack immediately. Does the ambushers’ insight reveal that the archer spotted them? If so, they strike and may surprise some characters. Can the ranger deceive the ambushers into waiting just a moment longer while covertly signaling the party? Ask what the alert characters do, and then call for checks to play the scene.

Distance factors into the situation too. In daylight, if the eagle-eyed ranger spots a group of yuan-ti hiding among desert rocks a half-mile ahead, then any surprise hardly matters. During that first round, no one without meteor swarm is in range to attack. The players can select the best angle of approach or can just avoid the monsters. Since yuan-ti have darkvision to 120 feet, they surely wait until night when most adventurers with darkvision see 60 feet and still suffer disadvantage to Wisdom (Perception) checks unless they carry a light source. Such scenes allow characters to show their special traits, like the drow character’s enhanced night vision that lets the party turn the tables.

For that ambush in darkness, you must judge how close the party will approach the yuan-ti before any characters can detect the snakes. Perhaps at 60 feet, allow the ranger leading the party one check at disadvantage due to dim light. At 30 feet, in the moment the monsters spring their attack, allow a second check for the entire party.

Ultimately, many ambush attempts lead into situations that demand DMs ready to balance distance, skills, and traits to create fun and exciting situations. An ’80s roleplaying game might have included a table that factored Stealth scores, Perception scores, terrain and lighting into a roll that revealed encounter distance. The authors of the Player’s Handbook skipped all that complexity in favor of simplicity. The approach relies on a DM’s judgement, but isn’t that part of what makes being a dungeon master fun?

How Well Do You Understand Invisibility in Dungeons & Dragons?

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Lately, I’ve played in some high-level Dungeons & Dragons games with enough invisibility to make me study how the feature works in the game. Despite all my years playing D&D—or perhaps because of them, invisibility in fifth edition often defies my expectations. I can’t be alone, so I wrote a quick guide to invisibility. At the end, I pose a brain teaser where invisibility and Mind Blank meets True Seeing.

D&D presumes that creatures can perceive the location of invisible creatures

The Player’s Handbook explains that when a creature becomes invisible, “The creature’s location can be detected by any noise it makes or any tracks it leaves.” This seems obvious, but the game design presumes more. In a Sage Advice segment, D&D lead designer Jeremy Crawford suggests assuming that creatures can usually locate invisible creatures based on sound and other clues. Signs like footprints on damp stone, the squeak of floorboards, the stir of tapestries, the twang of a bow, or the snicker-snack of a sword could all expose an invisible creature. The specific clues seldom matter, but unless invisible creatures attempt to sneak, something reveals their general location.

When we dream of becoming invisible, we tend to imagine roaming undetected, but the game’s assumption better matches reality. Even with your eyes closed, you can usually track someone moving nearby.

To avoid revealing your presence while invisible, you need to be sneaky. Outside of combat, that means Dexterity (Stealth) checks. Inside combat, that means taking the Hide action.

The need for stealth to go undetected benefits game play in two ways:

  • Invisibility helps characters, but they still need talent and skill to evade detection. Otherwise, invisibility would just make a better replacement for stealth.

  • Invisible foes become a bit easier to locate, making battles against them less frustrating.

Ultimately, the dungeon master decides when or whether to adopt the premise that creatures generally know the location of invisible foes.

A DM can rule that noises or distractions allow invisible characters to go undetected without stealth. Jeremy Crawford gives the example of an invisible wizard who doesn’t bother to hide from orcs. “The DM might decide that because the barbarian is screaming in their face and the rogue lit the gunpowder barrels nearby on fire and they just exploded, the orcs are not even paying attention and they don’t know where she is.”

To escape detection, creatures must hide

If creatures notice the location of invisible creatures, how does invisibility help? Normally, to hide, you need to be out of plain sight. Invisibility enables hiding anywhere.

Hiding prevents people from hearing you or otherwise discerning your location. “If you’re dashing around, swinging your sword in combat, or yelling to your friends, you’re not hiding,” Jeremy says. “People can’t see you, but they can certainly hear you.”

When you take the Hide action, you make a Dexterity (Stealth) check in an attempt to hide. If your check exceeds the passive perception scores of those who might notice you, you become hidden from them. If something imposes disadvantage on a passive perception score, the score is at a -5 penalty.

Someone whose passive perception fails to notice a hidden creature can spend an action to actively perceive them. Then, the action allows a Wisdom (Perception) check to beat the Dexterity (Stealth) check and locate the hidden creature.

Once you have made your check, you can move without making another check or spending another action to hide. That stealth roll from your Hide action continues to apply. The design aims to avoid slowing the game with rerolls.

Obviously, talking and other activities can ruin hiding. Attacks reveal your location. “If you are hidden—both unseen and unheard—when you make an attack, you give away your location when the attack hits or misses.” This rule’s wording makes clear that even though the attack exposes you after it hits or misses, you get the advantage of attacking while hidden. The Invisibility spell uses less careful wording, but its effect still lasts until you hit or miss. Jeremy says that the spell “doesn’t predict what you’re about to do.”

Invisibility benefits attacking and defending

You can attack a hidden and invisible foe by trying to guess its location. “If the target isn’t in the location you targeted, you automatically miss, but the DM typically just says that the attack missed, not whether you guessed the target’s location correctly.”

Even though creatures typically discern the location of invisible creatures nearby, invisibility grants powerful advantages. “Attack rolls against the creature have disadvantage, and the creature’s attack rolls have advantage.”

Because advantage and disadvantage cancel, if two invisible creatures swing at each other, they attack as normal with neither advantage nor disadvantage. Invisible creatures rarely trade blows, but blinded creatures in, say, Darkness or a Fog Cloud often do, and the offsetting advantage and disadvantage leads to normal attack rolls.

Invisibility blocks many spells from targeting you

Invisibility’s strongest advantage stems out of all the spells from Acid Splash to True Polymorph that only target someone the caster can see. An invisible creature gains protection from all these spells. Plus an invisible spellcaster can’t be countered. Counterspell is cast as a reaction, “which you take when you see a creature within 60 feet of you casting a spell.”

This makes Greater Invisibility the strongest defense spell for casters.

Occasionally, going unseen hinders allies. For example, Spirit Guardians says, “When you cast this spell, you can designate any number of creatures you can see to be unaffected by it.” When clerics cast Spirit Guardians, they can’t exclude the party’s invisible members from the guardians’ harmful effects. Likewise, the evoker’s Sculpt Spell ability requires the caster to see allies to exclude them from a spell’s area, so the invisible rogue gets more chances to show off Evasion.

Invisibility versus True Seeing and Mind Blank

True Seeing is a divination spell that grants Truesight and its ability to see invisible. Mind Blank makes its target immune to divination spells. Can someone affected by True Seeing see an invisible creature affected by Mind Blank? You might argue that the divination spell only affects the person gaining Truesight, and that their new perception isn’t blinded by a creature’s immunity to divination. Or does Mind Blank somehow cloud anyone attempting a divination spell? Do you have your answer?

Jeremy Crawford says True Seeing fails to reveal an invisible creature affected by Mind Blank. But in your game, you are the dungeon master. Your answer remains correct.

How to run an ambush

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Group checks and the ambush

In “How D&D Next almost made knowledge count” and in “Is it noticed? How to run alertness,” I discussed the inevitable success that comes when a group rolls to gain one success. The reverse of this phenomenon appears when a group makes a check and just one failure can drag down the effort. The designers of d20 role-playing games mostly ignore these issues.

Credit the fourth edition Dungeon & Dragons designers for introducing a group-check rule for some tasks. From a game-play perspective, I like 4E’s group-check rule because it makes some group tasks possible. From a realism perspective, I fail to understand how three stealthy party members cover the racket from the clanking dwarf and paladin. In this post, I ignore the 4E rule, which I’ve never seen applied to perception anyway.

No situation highlights the problems of group checks more than the ambush. Using the simplest interpretation of the rules, everyone in a group setting an ambush must roll to hide, giving all a chance to doom the effort with a single bad roll. When the targets of the ambush arrive, every target gets a chance to spot that worst hider.

Based on real life, you might suppose that ambushes typically work. The group setting the ambush has the advantage of planning, preparation, and surprise. They just sit out of sight until their targets arrive. Unless someone sneezes or the targets have x-ray vision, the ambush works.

Based on the game, the word “ambush” describes a imaginary event that can never happen.

In “Is it noticed?” I suggested a fix. I advised assuming that the targets of an ambush take-10 to spot it. In effect, you set the DC for the ambushers’ hide check based on the targets’ lowest take-10 to spot. While this enables one creature to set an ambush, it still fails when a group prepares an ambush and everyone must roll to hide. My method only gives a group a chance of setting an ambush if the GM either (a) requires just a single hide check from the worst hider or (b) relies on 4E’s group check rules for the attempt to hide.

In a comment, Sr. Rojo suggested a method for handling ambushes that I like better.

How to run an ambush

To run an ambush, follow these two steps:

  1. Allow the group setting the ambush to take-20 in their effort to hide.This reflects their time advantage, which lets them pick a good site and then arrange themselves for maximum concealment. When you set an ambush, you have time to work out the best hiding place you can muster.
  2. When the targets reach the ambush site, ask them to roll to spot. The DC to spot the enemy equals 20 plus the ambushers’ worst hide bonus.Unless the ambushers stink at hiding, the DC to spot the ambush may be unattainable for some targets, and will present a challenge to the rest. Unlike most group spot checks, this check presents a reasonable chance of failure. Rather than assuming the targets of the ambush take 10 on their spot check, you can let them roll, and still give the ambushers a fair chance.

As with any spot check, you can limit the check to those characters keeping watch and in position to notice. If the party wants to an ambush a company, only the few soldiers on watch get a spot check, not all 100 enemies.

Take 20 and the rules

“When you have plenty of time, you are faced with no threats or distractions, and the skill being attempted carries no penalties for failure, you can take 20.” – Pathfinder Roleplaying Game Core Rulebook, p.86

Some rules lawyers might argue that the hide attempt does not qualify for a take-20, because it carries a penalty for failure. I disagree. Unlike climbing or disabling a trap, the act of perfecting a hiding spot carries no penalty for failure. Your best hiding place may not be good enough, but that comes later.

Dungeons & Dragons fourth edition and fifth edition both lack a take-20 rule, so this method requires some latitude with the rules as written. In practice, if the players set an ambush and you tell them they automatically roll a 20 on their hide check, no one will gripe.

If the players walk into an ambush, you, as the game master, set the DC they must reach to spot the ambush. Even in a game without a take 20 rule, a DC equal to the ambushers’ worst hide bonus plus 20 makes a good target.

Next: Is it found? How to handle a search