Originally Posted by Grudgebearer
Grease spell does not create a flammable surface https://roll20.net/compendium/dnd5e/Grease#content.

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p.s. While drinking a potion is RAW an action, most games I've been in have home-brewed it to be a bonus action. Also, non-rogues don't get sneak attack in BG3, so that matches 5e rules.