D&D 5E Non-spell area effects vs. total cover

[TaranTheWanderer]

I think that even if an effect expands around corners, like a burst of flame, I’d use the rules for cover. Advantage to the save? I forget. But something like a gas would affect everyone equally, IMO. Other magic-like affects (negative energy for instance)would be on a case by case. But yeah, the description would be a good guideline of how to adjudicate.