Algorithm for spell casting chance

Hi,

great game, love it more than the original. There's just one thing that bugs me.

I used to always cast lvl2 spells and sometimes lvl3. But then something changed and now I cast spells on lvl1 again.
I don't know exactly how the spell casting chance is calculated but since even hero on lvl2 with 10 intelligence and no points in ritual can cast lvl2 spells with 30% chance why is my chance so low? It almost seems like it's one spell level off.

I have lvl 31 hero with 20 points in intelligence, 16 in ritual and 8 more to ritual from items and this is my spell casting chance.


Here's my hero with (hopefully) every relevant information. :]












Sorry for the amount of pictures, I wanted to be thorough.
And if my spellcasting chance is ok, can I ask how exactly is it calculated? If it's not a secret. :]

And thank you guys for the revival of an awesome game. :]

This might be caused by the Experimentalist/Methodologist perks. They change whenever you cast spells, and when they change, spellcasting chance and spell costs also change.