Lex Triumphant remains bugged and unable to be completed as of 1.0.24. I’ve definitely completed it several times over, it’s the last Heretic category penance I need. Please, I want that charm.
We’ll keep an eye out for more similar reports, but a quick check makes it look like this penance is not bugged, and most likely you still have some enemy types to kill 10 of.
If helps, dreg specials include:
Tox Flamer
Mutant
I’ve killed over 140,000 heretics. I’ve personally tracked the completion of this penance several times. It has to be a bug.