Critical Hit (X) "Attacks made with the Critical Hit (X) Special Rule have a chance to automatically cause a wound and inflict 1 extra point of Damage."
When any Hit Test is made for an attack with the Critical Hit (X) Special Rule, if the result of the Dice Roll, before any modifiers are applied, is equal to or greater than the value of X attached to this variant of the Critical Hit (X) Special Rule, then if a Hit is inflicted by that Hit Test, that Hit becomes a 'Critical Hit'.
A Critical Hit automatically inflicts a wound without any dice being rolled, counting as the roll of a '6' for any variable Special Rules that might be triggered by a Wound Test, and increases the Damage of the Hit by +1.
Fire Discipline When making a Shooting Attack for a Unit that only includes Models with this Special Rule, add +1 to the result of Hit Tests made for attacks in any Fire Groups that include more than five Dice or attacks and that have the Bolt or Auto Trait.
Impact (X) "On a successful Charge, a Model with the Impact (X) Special Rule temporarily increases a Characteristic by 1."
If a Unit that includes any Models with the Impact (X) Special Rule or any Models that have any Weapons with the Impact (X) Special Rule, and that Unit makes a successful Charge, then this Special Rule is triggered. Once triggered, until the end of that Assault Phase, when making Melee Attacks for Models in that Unit, each Model or Weapon that is selected for one of those Models, that has a variant of this Special Rule, gains a modifier of +1 to any Characteristics that is the value of X.