I don't know if this applies to any other classes or approaches, but regarding the Mystics and Corruption Thresholds
On page 108, under Shadow, Corruption Threshold is listed as "Your Corruption Threshold is equal to twice the total of your proficiency bonus plus your spellcasting modifier, to a minimum of 4".
On page 109 Corruption Threshold is listed as "Your proficiency bonus + your spell casting ability modifier x2"
So if I have a Attribute Modifier or +2 at first level...
The first method would result in a 6 while the second would result in an 8.
Unless I'm missing something, is this a discrepancy?