The final two sentences of the Web spell are written as follows:
The webs are flammable. Any 5-foot cube of webs exposed to fire burns away in 1 round, dealing 2d4 fire damage to any creature that starts its turn in the fire.
Does this mean that a creature in multiple Webbed squares takes 2d4 damage per flaming Web square, or just a flat 2d4?
This question arose recently as a debate in my game recently, centering around the word "any" at the start of the last sentence.
We were facing a gargantuan creature, and some of the players at the table, having read the last couple sentences, convinced the DM that since the spell said "any" 5ft cube exposed to fire, and with the casting of a fireball immediately after casting the web (second PC), ALL of the adjacent/occupied cubes of the web spell would ignite simultaneously, then each square occupied by the gargantuan creature (20ft base, matching the 20ft base of the web) would deliver 2d4 fire damage as it burned away in that first round.
At the time, the DM ruled this correct and subtracted 1/3 of the total cubes to account for the volume of the creature within the web (I would have subtracted 3/4 of the cubes at least for this - if this were the correct ruling to begin with).
This resulted in 64 cubes (the number of 5ft cubes in the 20x20x20 area of the web) minus 22 cubes (roughly 1/3 of that, rounded up) - total of 42 cubes each causing 2d4 fiber damage as it burned in one round. 84d4 fire damage. It added up to about 200 HP in fire damage.
I am thinking that it's likely the intent of this rule is that the TOTAL damage experienced by any ONE creature within a web spell effect suddenly ignited is - 2d4 fire damage.
RAW though - the English major within me can't shake that is says "Any", and the fire noted at the end of the sentence is referring to the fire of "any" specific 5ft cube, not the entire web, and a fireball would ignite all of them at once.
What is the correct interpretation of this spell, and how do you justify your answer?
"Because it is ridiculous to assume anything else," would not be a valid answer.
I have sent a tweet to Jeremy Crawford for an answer as well - but haven't received a response.
Finally - why do I need this? I'll be DMing this same group starting in a week and a half. I won't be allowing them to wipe legendary creatures in two rounds with this technique regardless - but I want justification on hand to shut them down when I say "no". I know, as a DM, I can do that anyway, but this is a game at my LGCS and I really want to keep things as peaceful as possible.