Half of the difficulty is preparation; if you know you’re fighting a bunch of necrosavants, you can just give everyone a shield and put your best fighters on the corners (who are more likely to get jumped by multiple necrosavants).
Other half of the difficulty is the lack of on-battle map formation adjustments; necrosavants become pretty simple if you can get your men into a square, but the fact that you start as two lines makes for hitting the juicy bowmen really simple.
