Diabolic Bulwork

Chaos Knights – Wargear Stratagem
Use this Stratagem in your opponent’s Shooting phase, when a CHAOS KNIGHTS model from
your army is selected as
the target of a ranged attack. Until the end of the phase, that model has a
4+ invulnerable save against
ranged attacks. If that model is a
WAR DOG-CLASS model,
this Stratagem costs 1CP; otherwise, it costs 2CP.