Manuals for playing as Dungeon

For a Dark Elf, two schools are usually developed: Chaos and Summoning. Of course, it's most logical to focus on Chaos, but when, for example, in long games there's no Armageddon, or there are other reasons preventing its use, you can utilize Summoning. For instance, the Phoenix, Phantoms, or Celestial Shield. In general, there are many options if the guild has good spells. However, most players focus solely on Chaos and seem to neglect Summoning. I think that's a mistake.