Listen/Spot Checks

Combining skill checks isn’t the only way to hack hack D&D’s skills. You can also split skills out into separate parts! Back in 3rd Edition, D&D used to have separate “listen” checks and “spot” checks.

This coalesced into one perception roll in 5th Edition.

Perception (5e)

Something Gained

Why would they do this? There’s a great reason, actually! When you make a player roll twice to accomplish the same task, they’re less likely to succeed. Effectively, you’re giving the player what we now know as “disadvantage.”

When 3e players had to make both a “move silently” check (to not be heard) and a “hide” check (to not be seen), we were basically making them roll with disadvantage (and split their skill points among different skills, but that’s another story).

Something Lost

What did we lose? When we dispense with granularity, we sacrifice mechanical opportunities to modulate the narrative. What’s the difference between being invisible and silencing your clanky boots if they’re the same roll?

A New System

Is there a way we can preserve the narrative dynamism of the different checks, without giving stealthy characters a huge disadvantage? Sure! We need a system that’s balanced by the numbers and doesn’t take forever to implement at the table. Here we go…

Hide/Listen Checks

We have two roles: the hider who rolls the stealth check; the senser who rolls the perception check.

The hider rolls 2d20:

  • Spot DC: higher roll + stealth modifier
  • Listen DC: lowest roll + stealth modifier
  • If you have advantage, use the highest result for both DCs.
  • If you have disadvantage, use the lowest result for both DCs.
  • Bonuses that would apply to your stealth roll (such as Bardic Inspiration, Bless, or Guidance), apply to both DCs.

The senser rolls 2d20:

  • Spot check: lowest roll + perception modifier
  • Listen check: highest roll + perception modifier
  • If you have advantage, use the highest result for both checks.
  • If you have disadvantage, use the lowest result for both checks.
  • A senser with keen sight can choose to use the higher die for a Spot check.
  • A senser with keen hearing knows the precise location of anything it hears.
  • A senser with keen smell can roll an extra perception die.
  • Vision, obscurement, invisibility, silence, and condition rules work as normal.
  • All creature features (class, feats, monsters, etc.) work as normal and any bonuses that would apply to your perception roll (such as Bardic Inspiration, Bless, or Guidance) apply to all checks.

Resolving the contest:

  • If the Spot check beats the spot DC, the hider is seen.
  • If the Listen check beats the listen DC, the hider is heard.
  • If the senser sees the hider, it knows its location.
  • If the senser hears the hider, it knows its location to within 5 feet, but the hider continues to be hidden. If the hider is targeted, an attack that would hit their AC has a 50% chance to hit (roll percentile dice). On a hit, the hider’s location is revealed.

As normal, you only need to match the Difficulty Class (DC) on your check to beat it.

Is It Balanced?

How do these numbers shake out? In order to make this system work, we should make sure it’s not too easy to reveal a stealthing creature’s location, but we should also make a stealthing creature impossible to find!

We’re generally satisfied with characters being better at a skill having the upper hand, so let’s make sure that a heads-up roll is balanced.

+0 Perception vs. +0 Stealth

To See: 18.42%

To Hear: 84.92%

This shows us that while you have a very small chance of identifying a creature’s precise location, but a great chance of hearing where they might generally be.

Remember that if you hear a creature, you can make an attack against it and you’ll have a 50% chance to hit, if your attack would have hit their Armor Class (AC). So, you also have an additional chance to reveal the creature when you hear them. You just need to triangulate with a hit! As a result, creatures with a higher likelihood to hit will reveal a creature more often. How does that shake out?

To Reveal: % to See + (% to Hear * 50% * % to Hit)

Here’s the different odds of revealing a creature based on a spread of chance to hit (from 25% chance to hit to 75% chance to hit, which covers most use scenarios in a bounded accuracy environment):

25% chance to hit: 29% to Reveal

50% chance to hit: 40% to Reveal

75% chance to hit: 50% to Reveal

I’m very satisfied with this spread. 29% to 50% gives a fair chance to spot a sneaking creature, but makes it likely that they will be discovered at some time during a sustained search. For example, if they are sneaking into a castle and need to get past several guards, or if they are hiding in the brush on the fringes of combat.

This gives the hider a fair chance to Stealth, which a reduced chance of success for the longer they try to keep up the ruse.

If you want to see us run some more numbers, check out the ThinkDM Patreon. It’s a great place for additional content, early releases, and personalized help for all our awesome patrons! The art for today’s post is the Royal Assassin card art from Magic: the Gathering, which has been used under the Wizards of Coast fan content policy.

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