Michael reacts to Mavra

"You dare," she whispered. She blurred and came at me. I took a breath, but she'd caught me on the exhale, and I had no time to unleash the crystalline blast I'd prepared.
Michael and Susan moved at the same time, hands thrusting past me. She held a wooden cross, simple and dark, while he clutched his dagger by its blade, the crusader-style hilt turned up into a cross as well. Both wood and steel flared with a cold white light as Mavra closed, and she slammed into that light as if it were a solid wall, the shadows in her hand scattering and falling away like sand between her fingers. We stood facing her, my azure power and two blazing crosses, which burned with a kind of purity and quiet power I had never seen before.
"Blood of the Dragon, that old Serpent," Michael said, quietly. "You and yours have no power here. Your threats are hollow, your words are empty of truth, just as your heart is empty of love, your body of life. Cease this now, before you tempt the wrath of the Almighty." He glanced aside at me and added, probably for my benefit, "Or before my friend Harry turns you into a greasy spot on the floor."


Grave Peril Chapter 28, Page 292