Ok, something weird just happened. Now, Piety tab is gone so I cannot verify, but Mystera just punished me when I killed the wraith boss, and I had more than 10 piety left, I have no Pact, so either she took more than 5 or somehow my Piety got wiped before the kill... EDIT: was there any tweak to how Mystera punishes mana burn?
Another one (not sure if bug or undocumented feature): casting BYSSEPS with my chemist also gives her +1 base damage.
i.e. I have 40/-15%; I cast BYSSEPS once to get 41/+15%; after next casting I have 42/+45%; then 43/+75%.
By the way, female elven Chemist is really cute!

"Thinker", just without the "ache".