Money is Light

Light is both absolutely necessary for most people's ability to function, and very scarce underground. There is no sun to provide free illumination; you must constantly expend fuel to make your own. Whjile Darkvision and Devil's Sight are effective in the relative safety of the cities, the 'Trails supress all ability to see in the dark. There are many different lamps and many different kinds of fuel, but all are equally in demand. As a consequence, light is also something valuable that can be traded. In fact, it is the one universal currency of the underworld. Instead of coins, we use the terms Lume and Daylume.


 * Lume (LM). Enough fuel to keep a lamp burning for one hour. Weighs one pound, and is equal in value to one gold piece in regular D&D economies.
 * Daylume (DLM). The approximate amount of fuel a person would spend to keep their lamp burning for one day worth of waking hours. Worth 20Lm.
 * Lesser Currency. Items that cost less than 1 GP (so less than 1 LM), can be paid for in small coins. Copper, Silver, and Electrum pieces still work the same way. For example, a silver piece that would normally make up 1/10th GP now makes up 1/10th LM.

Lumes are an abstract currency, a measure of a thing's worth. When characters exchange Lumes in play, they are actually trading fuel or objects that have their value defined relative to a certain amount of fuel.

To turn Lumes into actual light, you need a lamp. Your lamp is probably a prized possession, and you may want to give some thought to what it looks like. Lamps generally fall within the categories found in the Adventuring Gear section of the PHB, but ignore the refilling rules of those objects. Instead, deduct one Lume from the amount you're carrying for each hour the lamp burns.

You don't need to expend Lumes while in a city: public spaces are generally lit just well enough for people to be able to move around. When travelling through the 'Trails, however, it becomes very important to consider how many Lumes you're carrying. Your maximum carrying capacity equals (15 x your Strength score). You can own more Lumes than that, but only carry so many on your person at any given time.