Besieging undead armies

[krpeters]

Don't forget the Domkill option. Park an army to defend the territory and some priests to preach. Use your other forces to mop up his other territories, and he'll go away when his dominion vanishes.

[Peter Ebbesen]

Battlefield-wide elemental damage spells and Rain of Stones are other favourites once you have breached the walls if the enemy has thousands of weak undead.