“Quietly now. It’s a four-day journey to the other side. Let us hope that our presence may go unnoticed.”

Gandalf

This is a specific implementation of my Noise & Alert system, applied to travelling through the Underdark.

Part II of this post is up here: I Have No Memory Of This Place: Navigating The Underdark Through Your Senses in Dungeons & Dragons

What This System Tries To Do

• Implement the Noise & Alert system into the Underdark.
• Create meaningful decisions surrounding the resource of Time (and indirectly Resources): spending more time in the Underdark is inherently dangerous, leading to an increased chance of encounters (And thus spending Resources such as HP, Hit Die, Spell slots, Rations etc.). Rushing is taking a gamble with your Skills to spend less time navigating, but with the risk of going down the wrong path.
• The main vibe I’m going for is the Fellowship of the Ring navigating the Mines of Moria.

Noise & Alerts

The Underdark fits the criteria of the Noise & Alert system to a tee: it’s enormous, too big to ever fully conquer and it houses potentially infinite threats. It’s a dangerous, unwelcome location.

Out in the Open

When carefully considering the next path at the middle of a crossroads, trudging through unlit tunnels or climbing through long-abandoned ruins, the party is considered Out in the Open. To not be Out in the Open, the party can take 2 hours in a suitable location (old ruins, a dead end tunnel etc) to hide their tracks. This means that roaming threats will not find the party, and that they are safe.

Instead of the resource of Time, the party can also make appropriate Skill Checks (Survival, Stealth, Nature etc.). This should be a choice between

• Taking 2 hours without Skill Checks and making no Noise
• Making a relevant Skill Check to do it faster, but risking making Noise on a failure

Noise

“Noise” is the abstract measure of danger. It indicates the general attention the party has drawn so far. Keep in mind that the party is aware of the current Noise at all times; this is the big, threatening countdown clock (or countup clock) that adds tension. Whether it be Drow, wildlife or other dangers, the more noise the party makes (both literally and figuratively), the more trouble will find them.

Noise is gained through the following ways:

• For every 2 hours spent Out in the Open, add 1 Noise. This represents moving around, footsteps echoing down tunnels etc. This is not affected by moving quicker or slower; moving slow makes it more likely that some roaming monster stumbles across you, moving quicker makes more noise.
• Minor environmental obstacles can add Noise, varying from 1 to 1d6. Making jumps across a ravine causing some pebbles to fall down and splash into a lake deep down below, breaking open an ancient wooden door, or fighting/killing unintelligent wildlife all leave traces of the party’s passage.

Noise can be reduced by spending 8 hours while not Out in the Open, for instance during a Long Rest. At the end of the 8 hour period, Noise is reduced by 1d8.

Alert

Whenever the party does anything that might make the more intelligent and dangerous predators of the Underdark more aware of their presence, roll 2d12+Noise. This is the Alert Check, when all the accumulated Noise is brought to bear on the party.

Actions that might trigger an Alert Check:

• Loud actions in combat, such as casting Fireball
• Loud actions outside of combat, such as Pippin dropping a bucket down a well in the Mines of Moria
• Intelligent enemies sounding alarms. Be sure to telegraph this, so players have time to react (“The Drow is reaching for his horn”).

These actions might also add Noise individually.

The Alert Table

Check the result of the Alert Check on the Alert Table. This is an example of the one I use; it can look different based on the average increase of Noise and dice you roll for your Alert Check.

2d12+Noise	Result
1-12	No encounter.
13-24	Easy encounter in 1d4 minutes.
25-34	Medium encounter in 1d4 minutes.
35-44	Hard encounter in 1d4 minutes.
45+	Deadly encounter in 1d8 minutes.

For big, multi-day trips, I’d use a table like this:

2d12+Noise	Result
1-24	No encounter.
25-35	Easy encounter in 1d4 minutes.
36-57	Medium encounter in 1d4 minutes.
58-79	Hard encounter in 1d4 minutes.
80+	Deadly encounter in 1d8 minutes.

This makes Deadly encounters the average after 6 days, with the party gaining 24-8-1d8 Noise per day. You could easily make this table way more granular, or play with the randomness by changing the 2d that you roll.

In Summary

• Time is a valuable resource in the Underdark. Bad navigational choices cost time, and time = danger.
• Every 2 hours, or whenever the party is noisy, add Noise. Keep this in sight of the players.
• Whenever the party is loud, make an Alert Check and resolve the encounter.
• The encounters caused by Alert Checks can add more Noise and trigger more Alert Checks, causing a cascade of unfortunate events.