Thanks for the Dragonspire AssistanceI've gotten enough Thunderstone: Dragonspire help to rule the world, eventually. Thanks, as always, for your generosity.
Mostly, though, what I figured out is that I didn't have all the cards. That's not as simple as it sounds, though--there's a class of card called a "randomizer" that is a base deck you draw from to select certain classes of monsters and heroes to use in the game. I have far more randomizer types than I have classes, which means that when I tried to follow the instructions, I was missing all kinds of cards.
Except not exactly, because in the manual, it says that the randomizer cards were redone to be more visually distinct, so even though I'm playing a standalone expansion, the randomizer cards from the base set were included as well (because they were redone).
If I'd remembered that, today would have been far less complicated. After I went through and matched the randomizer cards to the classes I actually had in the set, life became much easier.