Greetings D&D Beyond and Community,

I was reading through the Hazards section of the new 2024 DMG and I had a question to some of you DMs out there.

The Yellow Mold description states when a creature is poisoned:
"While Poisoned in this way, the creature takes 5 (1d10) Poison damage at the start of each of its turns. The creature repeats the save at the end of each of its turns, ending the effect on itself on a success."

My question is on how to run this damage OUTSIDE of combat... How would you decide to handle the damage at your table?

As players are poisoned for 1 minute, my first thought was to have the player roll 10 Con Saves (10 rounds in 1 minute), telling them that they need to stop rolling if they get anything above a 14 and have them tell me the number of rolls it took to get a 15 or higher, then add up the damage per round and multiply that by the number of turns they were poisoned.

Thoughts?

I would reroll initiative with just the players, so the others could pitch in to make medicine checks or use healing spells.

Outside combat, i would just have the creature Poisoned by Yellow Mold  take damage, then make a Saving Throw. Rince & repeat 9 times until successful or dead, with allies possibly taking some action after it makes a Saving Throw. 

I agree with elgoblino. Roll initiative and do it in rounds. There’s lots of spells and powers that end the poisoned condition. Or even just cantrips like resistance to give them a boost on their saves. Let the players decide if they want to use those resources vs. hit points.

How I would handle the situation
'As combat ends, and the last enemy flees (or falls to the ground) you notice that [name of player] looks very jaundiced. The skin around their eyes has turned a sickly yellow colour.'

[Player name] Make another CON save.

If at this point the rest of the party don't attempt to intervene, I'll usually let them do what they intend to do...or at least start.

'As [Player name] takes a few steps forward, they dry heave their eyes bloodshot and yellowed.'

[Player Name] Make another CON save.

If at this point the player or party do not make any moves to assist the player character in question they've already had two warnings so that's all the party get. I've done my best as a GM.

'Okay party, for the minute after the encounter what do you all want to do next'

Then I turn player by player coming to each and ask what they want to do. When it comes to the poisoned player they get to start doing what they wanted to do, but they will be making CON saves as it all goes by. I tend to maintain initiative order post encounter for looting, healing, death saves and the like just to ensure no one character is running around doing all the looting. It also disincentives a solo character scouting ahead without backup. That's my way of handling it though.

Players shouldn't need more than a couple of warnings that something is wrong with a party member. Sadly 5.5e did absolutely nothing to fix the problem of it often being easier for player characters to be knocked unconscious and being healed than to prevent the knock unconscious in the first place. It's why we get the phenomenon both in 5 and 5.5e of yoyo-ing. Players at many tables will, get knocked unconscious before getting healed. Largely because there's no consequence for falling unconscious. I've seen conditions like this where parties have literally allowed their team members to be knocked unconscious or even die before rendering healing because 'the spells are easier that way' or 'well, that way I only burn a single spell slot'. 

This phenomenon is why I tend to run injuries in my games. If you get knocked unconscious once you get a minor injury, get knocked unconscious a second time between long rests and you're getting a major injury. It incentivises team gameplay dynamics, and encourages in combat healing.