Use the vampires as a night-time recon and hit and run force. They can move nearly unseen in mist form and small forces of them can shift out and ambush the enemies scout parties.
Make sure that one of your high level generals is a druid. Druids are the masters of army killing spells, creeping doom, fire storm, enlarged poison vines, and the list goes on. Plus the druid can sneak in and with natural spell and eschew materials cast as a tiny animal. No one expects the thrush/camp rat to drop hordes of insects and torents of flame on the troops.
The druid can also change into an elemental creature and burrow tunnels to help fend off an attack from dwarves/gnomes coming up underneath the fortress. The vampires can also fight effectively underground even if it is daylight above.
Make sure to have a contingent of clerics tasked with casting create food and water to feed your troops, also try to get a decanter of endless water for even more water supplies.
Make sure that one of your high level generals is a druid. Druids are the masters of army killing spells, creeping doom, fire storm, enlarged poison vines, and the list goes on. Plus the druid can sneak in and with natural spell and eschew materials cast as a tiny animal. No one expects the thrush/camp rat to drop hordes of insects and torents of flame on the troops.
The druid can also change into an elemental creature and burrow tunnels to help fend off an attack from dwarves/gnomes coming up underneath the fortress. The vampires can also fight effectively underground even if it is daylight above.
Make sure to have a contingent of clerics tasked with casting create food and water to feed your troops, also try to get a decanter of endless water for even more water supplies.