Potion of Heroism
Potion, rare · 2024 rules, SRD 5.2
10d4 + 20 Very Rare When you drink this potion, you gain the effect of the Gaseous Form spell for 1 hour (no Concentration required) or until you end the effect as a Bonus Action. This potion's container seems to hold fog that moves and pours like water.
Also in the 2014 rules (SRD 5.1).