The main campaign characters are only available when “main campaign” is selected. But with custom game, all of the characters are available regardless of which custom map is selected.
If you open a character with the wrong map, it strips all their class points, I’m guessing due to masteries being unavailable in the other mod. These class points seem to be gone for good, even if you open the character again with the correct mod. I would expect that items get stripped as well, though I’m not sure since I experimented with level 2 characters to see what would happen.
Is there any way to protect characters from this, or recover a character’s points (and items) if it does happen. As it is right now, I’m very hesitant to have multiple mods installed because it seems only a matter of time before I trash a character this way.