Bah, I should have learned about submitting turns at the very last minute.
I gave orders to break siege, had set every blood mage to spam Hellbind Heart, every Turkey in the fort and those that I could fly in from the other forts spam Control, with plenty of blood/astral gems for all of them, and positioned my units so that they cover the whole battle area, with the mages taking the back seat. Unfortunately, that took far too much time and I uploaded my turn about one minute too late or something. Blood 9 (Claws of Cocythus, Infernal Prison) is only a turn away for Mictlan, but that's too late, unfortunately. Midgard already has Blood 9 since quite some time, but since the ending is clear I don't want to waste time on the micromanagement any more now. I concede defeat.
Velusion, I'd be interested in the backup from last turn. I'd like to know if the orders that I prepared would have changed anything in that cataclysmic battle. Depends entirely on if and how many of his units I'd have managed to take away, with 20 mages spamming Control and Hellbind Heart.
Congratulations, calmon, and you really have to tell me how you could get those three forts up so early in the game and how many astral pearls you put into the Arcane Nexus.