it seems there are damage increase caps from intelligence for spells.
for instance going from 20 to 21 int has no effect on the damage of burning blaze or poison arrow, but lightning bolt still increased in damage.
i am guessing it has to do with the spell level since lightning bolt is the highest ability level of those spells.
still seems pretty crappy to be honest. with lone wolf and glass cannon i need more than one spell to cast per round, i want to target their elemental weaknesses, and on top of that some schools do not have high level versions.
there isnt anything after poison arrow or piercing ice shard for single target shots. also if something is weak to water i only have ice shard and piercing ice shard...
this is just a bad mechanic. its bad enough the only way to increase spell damage it to stack intelligence. you cant use crafting or have an extra skill to dump points into.
you just have intelligence, period. and its erroneously capped off at that.
after about level 12 you will just see the increase from level gains and thats the end of the show for spell casters.