Nasty Skulkers have the Always Strikes First and Armour Piercing (1) special rules in any turn they successfully charge an enemy in the flank or rear.
Source: Warhammer Armies Project: Unofficial 9th Edition (v2.2)
Nasty Skulkers have the Always Strikes First and Armour Piercing (1) special rules in any turn they successfully charge an enemy in the flank or rear.