The Hero's Path

I might have overdone it with the art preparation, but it's permissible in the final battle. The time seems to be roughly the same for everyone, almost two regular years. On a medium-sized map. In the Khan's quest, you only need to swim back and forth along the river near the city; elementals appear randomly. And the orcs only give another quest after you complete this one.

But to summon a demon, did you have to learn the summoning spell yourself?

That's one option, but it's enough to simply buy 3 runic spells and all the combat spells of levels 1-2. The catch is that one of them isn't sold by the demon but in a completely different place. You can also temporarily equip a staff with a summoning spell; that should also work.