Worldbuilding Implications of the Megadungeon as Literal Underworld

Last Week: Death in Depth Within the Mythic Underworld

Last week we explored how to make the mythic underworld a literal one as well. This adds a risk/reward mechanism without defanging death, and rescuing an ally from death provides a reason to delve deeper into the dungeon than the party otherwise would.

Does this concept mean that the dungeon is loaded with ghosts? Well, yes, but not the undead wraiths and banshees the PCs are accustomed to. The typical shade is an invisible, barely perceptible presence. 

But they can subtly influence the dungeon. A door slams shut when no monsters are nearby? A shade, agitated to a brief moment of corporality. A new torch goes out in a dungeon hall without so much as a gentle breeze? Snuffed by a shade.

But otherwise, shades are unseen and undetectable, even by magic that finds the invisible and the undead. The lost soul the PCs search for is the exception. Because of their personal connection to the dead adventurer, the PCs can spot a soul they know, once they are close.

"But my gear! But my loot!"

What if a PC dies, and the die roll indicates a result deeper than the deepest level of the dungeon? That means, at minimum, that the soul cannot be rescued until the DM decides to expand the dungeon. Indeed, in a meta sense, the deaths of powerful adventurers may be the genesis of many deep layers of megadungeons. Perhaps the newly created levels reflect the soulscape of the doomed PC that was banished there. The DM should create new levels at their leisure, and notify the players when a rescue is possible.

This works best in megadungeons where the dungeon becomes strange and inscrutable in its lower levels. Not just “very old tombs” or “entrance to the underdark” strange. Strange like ancient mythological beliefs that deep caves were literally the access point to the afterlife. The idea that the underworld is a physical space connected to the normal world, where one can go, and – at great risk – attempt to rescue someone is, of course, part of Greek myth, as well as various other mythologies. This idea could work best in a setting that folds the planes into the “real” world, rather than treating them as alternate dimensions or foreign planets, the way some of D&D’s settings have in the past.