Transhuman Physiology

Use this Stratagem when a GREY KNIGHTS
unit from your army that is not a VEHICLE or a
SERVITOR is chosen as a target for an attack.
Until the end of the phase, when resolving an
attack made against that unit, an unmodified
wound roll of 1-3 always fails, irrespective of any
abilities that the weapon or the model making
that attack may have.