Mold spores.
Dungeons get damp a musky and breathing becomes harder the more they stay in the dungeon as they slowly suffocate to the colorless, tasteless and odorless thing that is slowly killing them.
Every 5 minutes in the dungeon a save must be made, upon failure a point is lost from STR, DEX, CON.
Leaving the dungeon is the only way to heal as it will come right back after any healing. After half of each of the 3 stats is lost make a save of go unconscious. The character must make this save now every minute until the go unconscious. Only leaving the dungeon will allow them to be healed.
The deeper in the dungeon they go light from a torch will be more likely ignite natural gas will ups, or highly flammable substance that has collected on the walls from just a drifting spark.
Just turn the dungeon into the equivalent of a level 4 CDC biohazard.
Dungeons get damp a musky and breathing becomes harder the more they stay in the dungeon as they slowly suffocate to the colorless, tasteless and odorless thing that is slowly killing them.
Every 5 minutes in the dungeon a save must be made, upon failure a point is lost from STR, DEX, CON.
Leaving the dungeon is the only way to heal as it will come right back after any healing. After half of each of the 3 stats is lost make a save of go unconscious. The character must make this save now every minute until the go unconscious. Only leaving the dungeon will allow them to be healed.
The deeper in the dungeon they go light from a torch will be more likely ignite natural gas will ups, or highly flammable substance that has collected on the walls from just a drifting spark.
Just turn the dungeon into the equivalent of a level 4 CDC biohazard.