How would you deal with this in 5e? From spells I'm seeing you've really only got water breathing and air bubble from spell jammer. It's a pretty classic dnd trope so I'm surprised there's no solution.
The Necklace of Adaptation is probably the best option. It’s an uncommon magical item from the DMG that requires attunement.
While wearing this necklace, you can breathe normally in any environment, and you have advantage on saving throws made against harmful gases and vapors (such as cloudkill and stinking cloud effects, inhaled poisons, and the breath weapons of some dragons).
Poison immunity wouldn't help, at best it would prevent the panic feeling and hallucinations caused by breathing in CO, but the lack of oxygen would still kill you.
Gust of Wind would probably work well too, at least for a good chunk of the dungeon. 60ft long 10ft wide for 1m. That's going to be a lot of airflow. It depends on if there's a constant source of carbon monoxide or if it's a limited amount that can be cleared eventually.
How would you deal with this in 5e? From spells I'm seeing you've really only got water breathing and air bubble from spell jammer. It's a pretty classic dnd trope so I'm surprised there's no solution.
The Necklace of Adaptation is probably the best option. It’s an uncommon magical item from the DMG that requires attunement.
Poison immunity (monk), not breathing (various races), blasting open the entrances to increase ventilation
I'd argue that even with poison immunity, you'd need to worry about the presumed lack of oxygen.
Tortle Monk - immune to poison, ac17 at first level, and can hold breath over an hour.
Poison immunity wouldn't help, at best it would prevent the panic feeling and hallucinations caused by breathing in CO, but the lack of oxygen would still kill you.
Gust of Wind would probably work well too, at least for a good chunk of the dungeon. 60ft long 10ft wide for 1m. That's going to be a lot of airflow. It depends on if there's a constant source of carbon monoxide or if it's a limited amount that can be cleared eventually.
In Pathfinder, Air Bubble and Life Bubble would be the best choices.