A dungeon is a living system whose chambers, creatures, traps, and core work together closely enough to respond to what enters it.
Its chambers regulate the movement of matter and mana. Its creatures forage, defend, clean, reproduce, and carry signals through the dungeon. Traps put intruders under pressure, favouring those able to survive them. The core retains the pattern that organizes the whole system.
Delving helps keep this ecology active. As intruders meet resistance, the dungeon uses stored reserves, circulates matter, and tests how well its structures work. It learns from the intrusion. Delvers take part in a process the dungeon needs, but that need offers them no protection: the encounter can still kill them.