An interesting concept in this adventure: a campaign of three-linked adventures. The premise is that there are three clans that support Ashardalon (duergar, kobolds, and orcs) and that each clan must be defeated. One of the three clan leaders will be randomly (and secretly) selected to be the end boss for an adventure, and when you've completed all three adventures in a row, you win the campaign. However, if you lose against any of the leaders, you have to start the whole campaign over again. The good news is you get to keep all of the treasure found from adventure to adventure, and use some gold to buy new stuff.
All of that being said, each adventure itself is pretty easy. The clan leaders are more-or-less pushovers, with little in the way of offensive firepower or hit points (especially if the heroes are able to save their most powerful attacks until the end). It's essentially a survive until you turn over the right tile adventure, which players should be pretty familiar with at this point. Possible snags can be the number of monsters that turn up in the adjoining chambers, which does mean the clan leader should be killed as quickly as possible.
The description sometimes uses the term "adventure" as interchangeable with "campaign," which leads to some ambiguities. For example, it's not clear whether the boon cards are usable once per adventure or once during the campaign, or whether the players get to keep the boon card for use in future adventures (otherwise, the boon card earned at the end of the campaign would be useless).