Rock of Grimheim

It's necessary, it's necessary. But nothing prevents you from leveling up Chaos as a secondary school. It has a high chance of appearing, and there's a unique enhancement in the city that provides a 50% damage bonus for Fire magic. You can also create 80 spells on the map, taking into account a unit with the Channel skill. Unfortunately, this wouldn't be as effective in Dungeon. On the other hand, you can simply transfer Chaos to a mentor and take Darkness later. So, you can try a build with Chaos.