Ventras

I've run the demonsbane dungeons a few times (not Shrouded Ajanara though) and never saw it. Is it like a seriously rare boss drop, or a quest reward?

Hi, I know this has been discussed many times before, but I can find no current articles on where one might find these. I'm a fairly new player, so if acronyms and shorthand can be avoided I would appreciate a list of dungeons / merchant / locations these can be found at. Many thanks