Heart of the Night

The spell for summoning a ship is learned right next to the lake with the mermaid; succubi guard the book with the spell.

Apparently, you weren't paying close enough attention. It seemed like they were guarding some nonsense, and I just walked past (

That's how it's designed. Spells from quest givers are learned only if you have the necessary skill at that specific moment. But when you complete quests that give the most interesting spells, the mentor is already available.

That's true, but I didn't anticipate that. Or I forgot that he promised some spells. I would give spells regardless of the knowledge of schools; at a basic level, they are all useless, except perhaps Berserk, but this would allow you to adapt before the final battle without losing such important elements.

Was it the latest version of the map? And what army did Greta have in the battle with the Baal creature? If possible, could you upload the save file? I'd like to take a look at what the problem is; I think I fixed similar issues.

Yes, it's the latest version. I'm sure I have a save file. But I remember that Greta had a normal, fully equipped army, but she was stationed in the city's garrison. And when a hero is in the garrison, he is not visible as an "Object" on the map.

A very good start, good luck with the rest.