MALEVOLENT ARCING

Use this Stratagem in your Shooting phase, when
a NECRONS model from your army targets an
enemy unit with a tesla weapon. After making
that weapon's attacks, roll one D6 for each other
unit within 6" of that enemy unit: on a 4+, the
unit being rolled for suffers l mortal wound.
Leaping and coiling about its target with malicious
pseudo-sentience, the living lightning of these tesla
weapons coils outward like a slavers whip to lash at
yet more nearby victims.