I'm designing a monster which through virtue of high intelligence and me being evil, that has 13 class levels.
However, I also want to bump up the save DC on its special ability. The feat "Ability Focus" will do just that, however it is a monster feat and not a regular feat, so I do not know if it is technically legal to take a monster feat when the creature would normally get a feat for her class levels.
I'll probably do it either way, but I want to know if I'll have to explain it as GM fiat or not.