There’s been a lot of thought that Power from Pain isn’t giving the correct critical strike chance. I’ve played around with it and agree that something isn’t right.
I looked at the talent settings for Kerillian for the Power from Pain buff
Every other talent that grants critical strike chance uses the text ‘bonus’ instead of ‘multiplier’ when showing the amount of critical strike chance to give
See Pyromancer passive
I only have a basic grasp of how the code works but this could be reviewed in any case.