Walkthroughs for custom maps.

I've completed the first episode so far; I need to refine the report a bit before posting it here. I liked the map, although I have some comments and complaints for the author. The second episode is in the queue, waiting to be played...

What should I do in the first episode at the end of the game near the Conflux castle? I traded the Book of Fire Magic for Archdevils in the middle of the game, and now I can't open the passage to the castle. Also, I don't have enough parts for the Angel Alliance, although I might have given some away for a quest. Is this a trick by the author to confuse and make you give away the necessary items?