Deck of Dungeons
D&D 5E Loot Table Generator
D&D 5E Item List
Potion of Gaseous Form
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.
Source: SRD under the Open Game License v 1.0a