What kind of magic do you like?

Magic of Life (Intervention of the Gods (If 2 heroes in the squad know this spell, it's very difficult to defeat them), General Ward..., Prayer)
Magic of Haven (Hypnosis, Forgetfulness, Berserk)

Added 2 minutes ago

Chaos up to level 5 and such an orange book with spells. I just don't understand, does Chain Lightning hit both allies and enemies?

Absolutely, so you need to be careful with this spell, and instead of the book, I recommend the Staff of Chaos (+50% to magic power)

Added 12 minutes ago

But it can really harm the enemy with vampirism, Hand of Death, plague.

In defense of life.
There are spells like Sanctuary and Intervention of the Gods, and sometimes even such a simple spell as Cry of Heaven (Mass Holy Word).