Dungeon Clear

As the group wandered deeper into the dungeon, it became darker, and soon the light completely disappeared. They were forced to bring out the lamps to not lose their footholds.

There are those who might argue that lamps are a waste of money in a dungeon.

Exactly why?

Those who are trained as mages, a required class for many adventuring groups, are trained so that even without the help of any items except for their wand or whatnot, they could survive even in a dungeon. There are certain similar abilities in other classes as well, but that depends on preferences and inner potential.

In the hypothetical scenario of a well-balanced group, all the classes are grouped together in a dungeon with a difficulty they would struggle with but be able to clear. They eventually come across the boss when they are further into the dungeon, killing mobs while the mages light the way.