Counter-Attack (X) If a unit contains at least one model with this special rule, and that unit is Charged, every model with the Counterattack special rule gains a number of additional Attacks equal to the value in brackets listed as part of this special rule. If no value is listed then the unit gains +1 Attack.
If, when Charged, the unit was already locked in combat or has made the Hold the Line Reaction, the Counterattack special rule has no effect.