July 8, 2016

[D&D RAW] Hiding, Invisibility & Other Sneaky Business, Part 5: Finding the Hiding

This is the 5th part of a running series on Hiding in my new column for 5th Edition Dungeons & Dragons rules. You can read the previous post here. I will post a complete index of all the posts of the series at the end of the series.

In the previous post of this series, I looked into the exceptions to the Hiding and Unseen Attackers and Targets rules afforded by racial traits, class features and feats. This I think would have most of the bases covered, so it's time to look on the flipside of the Hiding coin; to detect a person in hiding.

This is an equally important set of rules to understand. As DMs, we are more likely to be on the finding end of the stick rather than actually hiding our monsters, because a cautious player (or one playing a Rogue character) are sure to try to make use of Hiding as it benefits their character. So this post is intended more for DMs, but players can benefit in knowing how a DM could make a ruling to detect your character in hiding.

There are several ways to find a hiding character.

Wisdom (Perception)

The most common way to discover a character in hiding is to beat their Dexterity (Stealth) with your monster's Wisdom (Perception) check. While this sounds straightforward, the confusion could arise when deciding to use your monster's Passive Perception or roll a Wisdom (Perception) check.

Looking back at the Hiding rules, it specifically mentions two types of scenarios when you make a Wisdom (Perception) check.
  1. Until you are discovered or you stop hiding, that check's total is contested by the Wisdom (Perception) check of any creature that actively search for signs of your presence.
  2. When you hide, there's a chance someone will notice you even if they aren't searching. To determine whether such a creature notices you, the DM compares your Dexterity (Stealth) check with that creature's Passive Wisdom (Perception) score, which equals 10 + the creature's Wisdom modifier, as well as any other bonuses or penalties.
For me, the main differentiation between these two scenarios is how actively the searcher is looking for the hiding character. So to put it simply, if the monster is not actively searching (or given good reason not to), they would use their Passive Perception.

On the other hand, if the monster is on alert, they should be entitled to make an active Wisdom (Perception) ability check to find the hiding character. I would rule that a monster can be alerted if a hiding character fails their Dexterity (Stealth) check to be unheard or hidden, but it does not mean that the monster can discover a hiding character immediately. It is only switching from Passive Perception to making active Wisdom (Perception) check, to beat the Dexterity (Stealth) rolled by the hiding character. 

I would also note that the Dexterity (Stealth) score of the hiding character is not changed until they are discovered, or choose to come out of hiding, and hide again. 


On Page 65 of the Basic Rules or Page 183-184 in the Player's Handbook,
Many creatures in the worlds of D&D, especially those that dwell underground, have darkvision. Within a specified range, a creature with darkvision can see in darkness as if the darkness were dim light, so areas of darkness are only lightly obscured as far as the creature is concerned. However, the creature can't discern color in darkness, only shades of gray.
This sense does not have a terribly wide implication on finding hiding characters more than preventing them from hiding in the first place. Since the first condition to be able to hide is to not be seen, a character that would normally be able to hide because they are heavily obscured by darkness, would not be able to in the eyes of someone with Darkvision, since it sees darkness as lightly obscured.

That being said, however, a character with the Skulker feat should still be able to make the Dexterity (Stealth) to hide in the darkness from a monster with Darkvision because it only requires the character to be lightly obscured.


Another sense that can discover a hiding character is through Tremorsense. The rules for it can be found in Page 4 of the Dungeon Master's Basic Rules or Page 9 of the Monster Manual.
A monster with tremorsense can detect and pinpoint the origin of vibrations within a specific radius, provided that the monster and the source of the vibrations are in contact with the same ground or substance. Tremorsense can't be used to detect flying or incorporeal creatures. Many burrowing creatures, such as Ankhegs and Umber Hulks, have this special sense.
From the description of this sense, it does sound to me like it would be the ultimate bane for all hiding characters, but Chris Perkins rule this differently.


Out of all the senses, I was unable to find any solid rules on it and there were few official sources that discussed this sense in relation to hiding. So this makes it an open territory for DMs to adjudicate between extremes. 

A more balanced approach that I might suggest is that while a character can still hide as usual from a monster with Tremorsense to become unseen (and gain its benefits), it can never be unheard or hidden. So a monster with Tremorsense always knows the location of a hiding character, but still needs to make the needed Wisdom (Perception) check to discover the hiding character, or have Disadvantage on its Attack Rolls as it normally would for unseen characters.


I kept this sense for last because it can be a little complicated, compared to the ones previously mentioned. First off, the rules for Blindsight can be found on Page 4 of the Dungeon Master's Basic Rules and Page 8 of the Monster Manual
A monster with blindsight can perceive its surroundings without relying on sight, within a specific radius.
Creatures without eyes, such as Grimlocks and Gray Oozes, typically have this special sense, as do creatures with echolocation or heightened senses, such as Bats and true Dragons. 
If a monster is naturally blind, it has a parenthetical note to this effect, indicating that the radius of its blindsight defines the maximum range of its perception.
Due to the reliance of sight as a condition for a character to hide, a character typically should be able to hide as though the monster is blind. But Mike Mearls still considers a monster with Blindsight to be able to 'see' a character within its radius.

This is also supported by Jeremy Crawford who gives the impression that a monster with Blindsight can perceive normally as long as the creature is within its radius and without cover.

Unlike Tremorsense though, if a hiding character is within its radius and is behind a cover, it still can become hidden, as Jeremy Crawford also supports this with these rulings:

So this helps to narrow down the limitations of Blindsight. For all intents and purposes, a monster with Blindsight behaves normally as a monster with sight, as long as the hiding character is within its radius. However, I would say that monsters with Blindsight should not be affected by obscurity when it comes to decide if the monster 'sees' the character trying to hide.

However, there is another element that can allow a character to hide from a monster with Blindsight, but I will talk about in the next post.

I hope this post would be helpful for DMs to figure out what do they have in their arsenal to discover hiding characters. But as you can see, there is not a lot of official rulings when it comes to these senses, so you may want to take your own time to study them before making your own rulings.

Speaking of making your own rulings, I'm about to bring all that I've learned together and put down a list of things a DM should consider about using the Hiding rules in their games. So see you in the next post!

[D&D RAW] Hiding, Invisibility & Other Sneaky Business, Part 6: DM Considerations

Last updated: 8/7/2016  

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