Wait... what would cause a spell to vary between 2 and 10 damage? It's a flame dart!
If a flame dart does 10 fire attack, its lowest damage should be 5.
Or are you including the resist chance into the range? Because it gets halved if it gets resisted, so 5 fire attack divided by 2 can do 2 damage.
What about spells that can be fully resisted? Are they just going to show 0-20 damage?
And what about resist values like fire resist, are those included? So many questions...