Do all of the cubes of fire from firestorm have to be contiguous?

@JeremyECrawford do all of the cubes of fire from firestorm have to be contiguous, or can you have separate pockets of two or more cubes?

— Grant Myers (@realgrantmyers) March 6, 2017

Fire storm—the spell's cubes must be contiguous. #DnD https://t.co/IwbyFYEUiV

— Jeremy Crawford (@JeremyECrawford) March 6, 2017