Pale one soldier-attack 8/old age

[Dedas]

Try magic +3 combined with magic penetration artifacts and then cast "weight of stones". Also darkness and utterdark (the last very high level though) work wonders as the enemies defense and attack will be halved if they do not have darkvision.
Another tip is to send in your human high protection high defense infantry first to raise the enemies fatigue and then send in the pale ones.

Any combination of this works.