I finally took down Michael :smile44:! First, his protectors were defeated, and then him.
I was in the city of Metatron (it needs to be taken last, because after a week, Michael will visit you with his "entourage") with such an army (I bought all the troops from all the cities, the map is completely cleared):
Imperial Archers - 644;
Guards - 707;
Vestals - 549;
Imperial Griffins - 262;
Radiant Beings - 280;
Celestial Warriors - 123;
Solar Crusaders - 223.
I started playing Heroes 6 with Anastasia, and because I didn't know, I pumped her up for tears instead of blood, which, of course, backfired in the final. An unholy spell with 7k damage, as someone mentioned above, would have been very useful, and by the way, I didn't capture the city of Metatron, but Michael still attacked. The army was as follows:
250 skeleton archers
220 ghouls
140 ghosts
106 archliches
76 rotting lamias
71 higher vampires
47 Fate Weavers
Michael defeated almost all of my stacks in 8-10 rounds, he had about half of his health remaining, and I only had archers left. I reloaded to a save, retrained Anastasia for defense, health increase, mass healing, general stone skin, and ice armor, and also upgraded almost all combat spells. I didn't use petrification, but I defeated the guardians purely with magic power (98 power) and the physical strength of the creatures. And I won this battle purely because of Michael. With his "last wish," he dealt 12500 damage to all the guardians and to himself. I don't know if this is a bug or what, but after casting it on himself several times, Michael took about 45-50k health off himself. I finished off the remaining 50. At the end of the battle, I had all the archers, 70 liches, and 18 spiders left. Thus, yesterday I completed the first final campaign with a hero rank.
I bought a "General Drain" scroll before the battle - it came in handy :smile20:!
PS Here's a screenshot of how I had Anastasia leveled up before retraining