Flames is doing 20 damage per second.
frostbite is doing 10 damage per second
sparks is doing 10 damage per second.
firebolt is doing 41 damage.
ice spike is doing 31 damage.
lightning bolt is doing 31 damage.
all runes are doing 50 so they are ok.
I am not wearing anything to improve fire damage but for some reason it does 10 extra damage. Dual casting Flames is quite OP on legendary even without the impact perk.
I need to get higher level spells to see if it is effecting them too.