Has no one ever in the history of pen and paper d&d ever said "I throw a jar of oil on the ground and light it on fire" and the DM had to figure out what the damage per turn fire does? LIke ever? It is not in the rule book on having a skill that makes fire by default, but with table top you can describe your actions and state your intent.
The DM then can determine based off ruleset the success and damage those actions may do (or could just overrule it with DM actions and say it did or did not work without a dice roll).
So in this scenario, Larian is the DM and they are determining the application of the 5e rules and adapting them to match the environment they created.
Just because you never thought to throw fire on the ground doesn't mean it can't be done in 5e.
I looked it up and apparently the 5e rule state on page 249 that falling in a fire might do 1d10 - 24d10 depending on the severity of the improvised damage from hot coals and a pit of fire to elemental plane fire dmg, so imagine that type of fire dmg, this is tame in comparison.
Now useful feedback is: - Surface effects stay TOO long. - Saving Throw per turn in surface effects (like oil/fire/poison) to see if you don't take damage or slip or fall (this already exists, but fire seems the easiest to get use out of) - Maybe make Firebolt and such fire effect apply on the target but not on the ground, unless specifically ground targeted (then the target only takes dmg from spell application and not both spell and ground). - Elevation advantage/disadvantage vs Cover fire system (I'm fine with elevation, but no strong decision one way or the other) - Always strafing around to get behind to gain advantage (maybe make any flanking movement in melee range cause a roll for dex so that not everyone is spinning around or jumping around in combat?)
Overall I actually like what is done in the game, but in order to listen and compromise instead of 2 sides just shouting at each other, I feel evaluating these topics like this would help both types of players.
There actually are specific rules for throwing oil on the ground and setting it on fire. It deals a straight 5 fire damage to a creature that enters or ends its turn in the fire, and burns for 2 turns. It doesen't set you on fire or anything.
This is worded such so that if you set it on fire at a creature feet it can move out of it, because the correct way to do that is to hit the creature in which case they take 5 more fire damage from the next fire attack. It's an area denial tool, not a "I win" tool. Fire surfaces right now are "I win".
