Strategy and tactics principles for Heroes of Might and Magic IV.

Yes, that's correct. Generally, that's how it works, but there's one Castle in Heroes 4 that's an exception. Or rather, it's not even a Castle, but a type of hero. These are the heroes of the Chaos Castle, who have Scouting and Stealth skills. When starting with these heroes, it's possible to complete the game without an army at all (considering that you'll encounter powerful artifacts along the way, such as the Armor of Regeneration, Stunning Arrow, etc.). Let me give you an example: I once played using this tactic for the Nature Castle (although the difficulty level was "Master," not "Champion"). I chose a hero not from the native Castle, but a Rogue from Chaos. By leveling up Stealth to level 4 (collecting all the chests for experience and finding skill stones), I could already capture all the mines and collect all the artifacts on the map without any consequences, including the Stunning Arrow, Stunning Mace, and Armor of Regeneration. At level 10 (having Warfare at level 3 and Archery at level 2), I could easily defeat monsters of level 3 with a single hero, no matter how many there were. At level 20, after learning Magic of Life to level 1 and having the "Healing" spell in my arsenal, there were no more invincible monsters on the map for me. I could even defeat those that Scouting indicated would "crush my army." The only obstacle was the garrison of 50-60 Black Dragons, which was set up by the map creator (the map is "Prisoner of Dragons" in the "Alexander" expansion). Overcoming this was an impossible task for me, even with the decent army I had accumulated in the Castle by that point. Now, I'm trying a tactic with a "Dark Priest" (Magic of Life + Magic of Death) – this means vampirism during the hero's melee attacks, and if the "Regeneration" spell appears in the Castle of Life, there's no need to rely on the Armor of Regeneration. In general, the tactic of developing a hero into a "Dark Priest" is very promising – the arsenal of Magic of Life will make you almost invincible, and Magic of Death will add some extra tricks. And, of course, don't forget about Warfare. However, there's a big drawback to this tactic: you naturally have to take the hero only from the Castles of Life, Nature, or Death. And if you encounter Magic of Life or Death (which are opposite to each other) on your development path, it may take a very long time. You might get lucky if there's a magic university with the school you need nearby. But then there's another problem: universities are guarded by quite strong level 4 monsters, and you won't have Stealth because the hero is from a different faction. You'll have to gather a strong army, developing on other monsters, and then there's a chance that you won't be able to combine Magic of Life and Magic of Death, as one of the schools will already be at its maximum level, and the other won't appear. Can you suggest how to get a "Dark Priest" with minimal losses?