All models with Daemonic have Fear, Immunity (Poisoned Attacks, Psychology), Magical Attacks (including all weapons) and Ward save (5+) (except mounts). In addition, they are also subject to the following special rule:
Daemonic Instability: When a unit of Daemons loses a combat it must take a special kind of Break test called a Daemonic Instability test, instead of taking a normal Break test. To do this, use the following procedure:
1) Calculate combat result as normal and roll 2D6.
2) If the dice roll is a double 1 or double 6, something unexpected happens:
Double 1 Reality Blinks: All Wounds suffered by the unit this Close Combat phase, including any Wounds suffered by characters that have joined it, are restored, and any models removed as casualties in this phase immediately return to play in their earlier positions. Wounds restored in this manner still count as having been inflicted for the purposes of combat results.
Double 6 Banished! Remove the unit from play as a casualty.
3) Now (assuming the unit has not been wiped out when resolving a double 6) apply the difference in combat results as a penalty to the Daemons' LD characteristics. For every point by which the 2D6 roll exceeds this modified LD value, the unit suffers one additional Wound, with no saves of any kind allowed.
If characters are present in the unit, the controlling player first allocates Wounds to the unit (up to their current Wounds), then divides remaining Wounds as equally as possible amongst any characters. Once all Wounds have been allocated, the penalty to the Daemons' LD is discounted. They can, be rerolled if the battle standard is within 12", use the General's Inspiring Presence rule, and/or be tested on unmodified LD if the unit is Stubborn or Steadfast. If a Daemonic unit somehow is Unbreakable, it takes no Daemonic Instability test.