I have a character who can do significant fire and/or cold damage. But I am curious about how these elemental attacks work on materials:
1- How much cold damage does it take to freeze water? I realize most spells are instantaneous, but they last long enough to freeze creatures to death. Even so, there are some lingering spells that do cold damage over time (rounds or even minutes). The best I have found is the spell "Freezing sphere" that seems to imply 11d6 cold (wizards could cast this at 11th level) is enough to freeze water in it's area up to 6" deep instantly.
2- How much cold would it take to freeze magma/lava? I don't see any stats for liquids or semisolids in the PRD.
3- What happens to solid materials when they are destroyed by ice or fire? For instance, if I hit wall made of stone (Hardness 8, 15hp/inch) with a spell that dealt 72 points of fire damage, it should be able to destroy 2 inches of stone. (a) Is that stone now melted into lava? (b) If the same damage was done to a flammable object, is it now on fire?
4- How much fire damage does it take to start a fire? The SRD mentions instantaneous effects not being able to start fires, but what about ones that last rounds or minutes?
5- Can cold damage put out a fire? It can kill a fire creature and end a fire spell, so it seems like it should be able to put out a fire.
Anyone?
You are on very GM friendly territory, better ask him. There might be some rules for elemental damage to destroy objects (might bypass damage reduction, perhaps?) but I doubt that even half your cases are covered by the rules.
If I were your GM I would cover it on a case by case basis.
