quick question concerning spell damage

[Boron]

do battle spells have a 2d6 oe roll added to damage too or only the listed damage + an increase for higher magic skills in the path required ?
flare e.g. has 19+ ap damage . i think the + is only +1 / level above the required casting path levels .

or do they increase non linear ?

the main conclusion i want to draw out of this is whether fire spells can kill high protection units or not .

cause without a 2d6 roll a fireball and the likes can barely scratch a 30+ protection sc while a couple of lighnings probably kills him .
a lightning bolt has furthermore +7 precision so hits often .

ok incinerate is amor negating too .

but the mass destruction area affecting fire battle spells are all only ap .
when you have researched them they will be barely useless already because almost no weak troops will be left on the battlefield while orb lightnings or wrathful skies do massive an damage .