He knows because Jay has told him her mom has a third power. But, even Jay does not know what her mothers third power is only that it is powerful enough to keep her as coven leader.
I think that sounds perfect ^.^ Though he might not take kindly to it at first.
He thought he sent out his darkness like he did before, to engulf her light, but instead he threw out a solid wall of darkness that actually collided into her shield and bounced back to him. I did not really communicate that clearly, I apologize. I can redo the ending if you wish. ^.^