A unit made up entirely of models with this special rule may perform a Flanking Assault as described on page 311. Certain Faction or unit special rules may present other options for the deployment of units with the Outflank special unit.

Stubborn

When a unit that contains at least one model with this special rule takes Morale checks or Pinning tests, the unit ignore any negative Leadership modifiers. If a unit is both Fearless and Stubborn, the unit uses the rules for Fearless instead.

Legiones Hereticus (Emperor’s Children)

Lords of Profligacy
After a Shooting Attack has been resolved against a unit composed entirely of models with this special rule, if that unit is not Falling Back, its controlling player can choose for it to become Stupefied. If a unit becomes Stupefied while Pinned or affected by the Blind or Concussive (X) special rules, it ignores the effects of these while Stupefied.

Stupefied
A unit that is Stupefied can only fire Snap Shots and cannot make Reactions in any Phase. If a unit that is Stupefied has a Charge declared for it, then that Charge is always considered to be Disordered. Furthermore, whilst Stupefied, all models in that unit increase their Strength Characteristic by +1 and when a model in a Stupefied unit suffers an unsaved Wound, it can make a special Stupefied roll to ignore it. Stupefied rolls may not be taken against attacks that have the Instant Death special rule. Roll a D6 each time an unsaved Wound is suffered. On a 6+, the unsaved Wound is ignored. On any other result the Wound is applied as normal. Add 1 to Stupefied rolls made for units which have the Fearless special rule. A Stupefied roll is a Damage Mitigation roll – any model may make only a single Damage Mitigation roll of any type for any given Wound.
At the end of its controlling player’s following turn, the unit is no longer Stupefied. Whilst it is Stupefied, a unit does not take further Morale checks in the Movement phase or Shooting phase and cannot be Pinned. If the unit is forced to move, for example, if it has to Fall Back, it is no longer Stupefied. If assaulted, the unit will fight as usual, but enemy units do not receive the Initiative penalty for having Charged a unit through Difficult Terrain, even if the Stupefied unit is in Difficult Terrain. If a unit becomes Stupefied while making a Charge, then that Charge continues as normal, but is automatically counted as Disordered. Units that are locked in combat can be Stupefied, but take Morale checks in the Assault phase as normal and if forced to Fall Back are no longer Stupefied.