In other words: you need to have proper spells first to use Higher Magic. But I think you shouldn't have big problems to continue this game on normal as this mode is "pretty easy", especially if you do not care too much about losing some units.

I said I am not too experienced in KB:TL because I am doing my literally third run. First was on normal, unfinished (because I decided it is too easy). Second was on impossible/no loss, unfinished (because I failed with Furious Paladin Blessing of Crypts quest / Resurrection scroll reward and coundn't manage to survive later). I hope I'll finish the game this time.

I haven't finished it yet, I do try not to lose too many units, since most of them are not available anymore.
First try was hard, too much trouble for me, normal is ok, but still need quite some tactics it seems, sacrifice is rather useless and too expensive, but I'll manage.

The resurrect scroll from furious paladin is only for paladins I heard, I won't have access to a scroll for a long time still.

Yes, that was me who told you that - I was so unhappy and was looking for answer myself at that time (also, to be precise, even if you are paladin it is not 100% guaranteed to get it from Furious Paladin but only paladin can get some more units/items to buy as Blessing of Crypt reward).

Also, in my current game I've found scroll on Islands of Freedom. By scanning over 100 games I can tell that this is the earliest possibility when you can get it. You can't get Resurrection scroll in first game areas unless you are paladin (or you have acquired Count title, but it is still further in game).

Yea I noticed that on my scans too, and after getting to the mines, I still am a stupid Baron, so silly :D