Expendable (X) "A Player scores less Victory Points when they destroy a Unit that includes only Models with this Special Rule."
The number of Victory Points scored by the opponent when a Unit that includes only Models with this Special Rule is entirely Removed as Casualties, for example, as part of the Vanguard (X) Special Rule, First Strike (X) or Slay the Warlord (X) Mission Special Rule, is reduced by the value of X, to a minimum of 1. If a Unit includes Models with different variants of this Special Rule, then the lowest value of X that was present on any Model in that Unit at the start of the Player Turn in which the last Model in the Unit is Removed as a Casualty is used to determine the effect of this Special Rule on that Unit.
Note that, if, at the start of the Player Turn a Unit includes any Models that do not have this Special Rule, then this Special Rule has no effect on that Unit for the duration of that Player Turn regardless of how many other Models in the Unit may have any variant of this Special Rule.