Some ideas: raiding, seiging, spell AI and more..

[Soapyfrog]

Graeme Dice said:
Three castings of raise skeletons gives more troops than a single casting of undead horde. Two castings of animate dead gives more troops than a single casting of undead horde.

Yes however you dont have the luxury of time since the doom horrors will be eating your casters... actually they will eat them anyway since the skeletons run forward and the horrors fly in behind them and start to dine. Seriously I found this tactic wildly ineffectual.

And its even worse whent he doom horror(s) are not alone.

Sure, but you have an infinite supply of them from the combination of drain life and raise skeletons. After all, the AI casts drain life as soon as its fatigue nears 100.

Did I mention drain life didnt work on the doom horrors?