Let the Galaxy Burn!

Until the end of the Turning Point, each time a
HERETIC ASTARTES operative is activated,
once during that activation, in the Roll Attack
Dice step of a combat or shooting attack, if it is
targeting the closest valid target, you can retain
one of your attack dice results of 5+ that is a
successful hit as a critical hit (if you could
already retain one of your results of 5+, you can
retain one of your results of 4+ instead).