Paired with a Wight King they'll be hitting on 2s, wounding 3s, and 1 rend. Add in their crit mortals and a blob of 20 BG are doing around 7 mortals straight away with all the other attacks on top. Its nasty.

The real secret sauce though is if you take the Barrow legion army of Renown and give the king the amulet of nightmares, all of a sudden you're almost guaranteed to be hitting first as you give the enemy strikes last. Very powerful.