Question about the map "Empire of the World".

If I remember correctly, I found the Angel Wings in Dragon Utopia, but I don't remember exactly which one. One of them had already been cleaned. I didn't bother with the Alliance; I probably just flew over using the wings. I didn't pay much attention to these moments because, for the first third of the game, my main goal was to keep the heroes I rescued from the dungeons alive (some of them unlock towers with a question mark). For the next two-thirds, I made sure the computer didn't steal my skeletons, and in the last third, I made sure the computer didn't "take" my liches and that I didn't have too much money lying around. I bought resources as you suggested, and that's how I got through the game to the end. In the final battle, the liches "pacified" the enemy, although I could have simply flown over to a tower and killed one skeleton in the northeast. I read about this task after winning the final battle, but for some reason, they still didn't give me the victory. I tried Sacrifice; it's a decent spell, I agree. I also sacrificed some cavalry units, but I didn't have time to resurrect them with Archangels; I couldn't find the corpses... or did someone else die in the place where the cavalry units were standing? I must have missed that. The Power Field spell disappears after one turn. If I equip an artifact that increases the duration of spells, will anything change? I'll answer myself. I equipped the Composite Artifact, the Ring of the Mage, which adds 50 rounds to the spell duration... but the Power Field still disappeared after 1 round.