[Vicious Love]

Also, the computer is terrible at fighting either of Ermor's undead themes. If there was more than one AI player in your game, Ermor likely took them out very early on, and thereby became even more powerful than they'd be in a 1 vs 1 game. Not that they're not nasty enough to begin with. Still, nothing a whole bunch of priests, Herald Lances, fire mages, astral mages and so forth can't fix.
Also, when fighting the Ashen Empire, keep in mind many of your astral spells(specifically Mind Burn, Soul Slay, and Enslave Mind) will not target mindless units. Since only AE's commanders have minds, this means a dozen or so astral mages can take out all of the enemy's commanders in a turn or two of combat. The rest of the AE army should disintegrate shortly thereafter.