My core arrived yesterday! Played the demo adventure (more different than I thought). I'm going to start again on Normal. Since I also have Crimson Throne can I use level 0 cards from that set as well? I'm thinking of it like the Character add-on, where you need the extra stuff; especially with a large group. Or should they stay separate?
You are definitely AOK to do whatever you want there. If you have a lot of characters or are interested in the additional boon diversity, go for it.
There are some boons in Curse that aren't quite as helpful for Dragon's Demand, such as those that require Harrow suits or work against Plague, but the game runs well with or without them included and all of the level 0 boons should be useful regardless.
The Dragon's Demand story book tells you to add the Curse of the Crimson Throne cards if you're playing with 5 or 6 people (top of page 2), or if you're playing a character from CotCT (Build the Vault, page 3).
I'm sure it would work just fine if you added them when playing with only 4 Core characters as well.
(Note that Build the Vault, page 3 tells you to add all the Core boons to the vault, but to only include level 0-1 Core banes and level 0-1 CotCT cards)
Thanks to both! I need to READ everything. Too eager to get started!