Explanations for how magic works?

[anthon]

I've never tried to work out how hot a fireball must be to do the damage listed because I was pretty sure I wouldn't like the answer.
So magic microwaves works quite well. It could even explain why 5th ed fireballs don't light fires - It raises the temperature briefly, then lowers it again. Unfortunately this seems like it has the least "Off Lable" usage potential, but I'm sure a creative party would come up with something

your edition fireballs don't light fires? T__T

"besides causing damage to creatures, the fireball ignites all combustible materials within its burst radius, and the heat of the fireball will melt soft metals such as gold, copper, silver, etc."
silver: 1762F - high thermal capacitance
gold: 1945F - very high thermal capacitance per cm^3
copper: 1983F - high thermal capacitance, rapid thermal transfer