Rule: Drowning and Suffocating
Summary |
You can hold your breath for a number of rounds equal to 5 + your Concentration⚙️ skill proficiency (or your CON / Constitution).
Reduce your remaining air by 1 round at the end of each of your turns, or by 2 if you attacked or cast any spells that turn. You also lose 1 round worth of air each time you are critically hit or critically fail a save against a damaging effect. If you speak (including using an ability with a Verbal component) ,you lose all remaining air.
When you run out of air, you fall Unconscious and start suffocating. You can't recover from being unconsciousness until you are given air. Otherwise, you must attempt a DC 15 Fortitude save at the end of each of your turns. On a failure, you take 1d10 Force damage, and on a critical failure, you take 2 death saving throws. On each check after the first, the DC increases by 3 and the damage by 1d10; these increases are cumulative.
Once your access to air is restored, you stop suffocating and are no longer unconscious (unless you're at 0 Hit Points).