Skyfire

Use this Stratagem in your Shooting phase, when
a HUNTER model or STALKER model from
your army is chosen to shoot with. Until the end
of that phase, that model can only target units
that can FLY; when resolving an attack made by
that model, add 1 to the hit roll and wound roll,
and on an unmodified wound roll of 6, double
the damage inflicted