Warp Lightning

{t} If successfully cast, pick 1 enemy unit within
13" of the caster and visible to them. That unit suffers
D3 mortal wounds. Before making the casting
roll, you can say that this model will use its
warp-power accumulator to augment the spell.
If you do so and the casting attempt is successful
and not unbound, the spell inflicts D6 mortal
wounds instead of D3. However, if you do so
and the casting attempt fails or is unbound, this
model suffers D6 mortal wounds.