Tonight, I played more Circle of the Moon. I did first play my original file (which I copied, to try to preserve its "integrity"; however, I probably have leveled up after I beat the final boss) first, and in fact uncovered a slight amount of the map I somehow missed before. While doing that, I found where the save spot was in the area I described in my above post.

That helped me in my magician file. I did pass through that area and beat the boss at the end. That gave me the Roc's feather. That has an effect similar to finding the bat spirit in SotN (or, to be even more precise, it's like Richter's super jump, though that doesn't need to be earned), in that now you can "fly" and any area of the castle can be reached. After that, I was able to go back and find a few places in the castle I couldn't previously reach, and earned some MP and HP increases. I also made it to another boss (Hugh), which I spent a long time fighting, but still lost.

In some ways, Magician mode is like an easy mode, in other ways it's like a hard mode. The beginning of the game tends to be easier, since you have magic spells that can kill early bosses almost instantly. But as the game goes on, the enemies become more powerful, and you don't become so much more powerful. I experimented a bit, but I couldn't find any spell that was particularly effective against Hugh. (There are still some spells I don't know how to use, though, such as summons).
I LOOOOOOVE Flying Omelette!!
Crawl and 1000