Auto-translated
My opinion:
1. Inga (Carli Ingvar) (level 25)
2. Perfect knowledge of runes, the greatest rune;
2.1. Masterful Chaos Magic: fire - secrets of chaos - pyrokinesis
2.2. Masterful Defense: evasion, resistance, resilience
2.3. Masterful Education: ....(preferably in mentoring)
2.4. Advanced Luck: magic resistance, dwarven luck;
2.5. Masterful Enchantment .....
Priority should be given to artifacts that increase magic power, and at all costs, find the Phoenix Cloak with +50% fire damage (fortunately, it's not that rare). And, of course, Armageddon should be available. If you're leveling up Inga, you won't have problems with runes. If you're leveling up other heroes, look for a rune that provides resistance to 2 random elements. And incorporeality will also be useful. Use the hero to cast Armageddon, and have your troops wait on your territory, preferably focusing all attacks on Unicorns. After a series of Armageddons, Ents may survive, but they are much slower and not as dangerous, so you can leave them for last.
If you managed to level up mentoring, then before the main hero attacks, prepare several kamikaze mages to thin out Wingael's archers or use Armageddon (if available).
P.S. There is also an option with the School of Darkness, but it is very difficult for dwarves to acquire.