Your dark spells are remarkably potent, breaking through shadow resistance more readily than normal.
Prerequisite: Dark Penetration.
Dark spells you cast are harder to resist. Any shadow resistance on a creature is considered 2 less when determining damage from a dark spell, but is considered 2 more with light spells. This bonus and penalty stacks with the one from Dark Penetration.
Special: You can gain this feat only once and this stacks with the Spell Penetration feat.