ToME: the Tales of Maj'Eyal

If your character has the Cunning/Scoundrel generic category tree previously locked, taking the Tricks of the Trade prodigy unlocks the tree but at 0.9 mastery, effectively downgrading the mastery if it was higher than 0.9 while locked.

Well it's still happening in 1.6.7. Man I just learned that the hard way.

I understand why it was called a "bug" in the title here but I personally claim it's just a straight-up bug without any quotes. The description doesn't make it entirely clear what the prodigy will do if you already have Scoundrel (and it's locked), but it's very reasonable for the player to expect the prodigy to be generous and just unlock it without any downgrade. Also the prodigy isn't all that great to begin with, and it can't really bear any extra flaws. It definitely should at least be changed to remove this harsh downgrading behavior.

Oh and here's another thing: If you had a locked Scoundrel category but a point or three in the talents anyway (because you'd escorted some repented thieves), then I guess your actual TALENTS would substantially weaken, not just your skill in the category. Yeah that seems seriously buggy.

(I guess that would happen too even if you didn't start with 1.3 in the category?? Because escort quests normally give you 1.0 skill each, not 0.9? Maybe I'm remembering wrong. But it'd be really annoying for a rogue, to lose that 0.4 skill in a talent that you already knew, as punishment for taking the wrong prodigy.)