Sets ghost on fire

Michael shouted, and swept Amoracchius at the spirit. The great blade bit into her back with a wooden-sounding thunk and made her arch up, screaming in pain. It was a deathblow. The white light of the blade touched her spirit-flesh and set it alight, sizzling away from the edges of the wound. She twisted, screaming in fury, and the motion jerked the blade from Michael's hands. Agatha Hagglethorn's blazing ghost prepared to fly at his throat.
I sat up, seized the sack of ghost dust, and with a grunt of effort swept it at the back of her head. There was a sharp sound when the improvised cosh struck her, the superheavy matter I'd enchanted hitting like a sledgehammer on china. The ghost froze in place for a moment, her feral mouth wide - and then toppled slowly to one side.
I looked up at Michael, who stood gasping for breath, staring at me. "Harry," he said. "Do you see?"
I lifted a hand to my aching throat and looked around me. The sounds of baying hounds and thundering hooves had gone. "See what?" I asked.
"Look." He pointed at the smoldering ghost-corpse.
I looked. In my struggles with Agatha's ghost, I had torn aside the prim white shirt, and she must have ripped up the dress when she'd been crashing through sidewalks and strangling wizards and so on. I crawled a bit closer to the corpse. It was burning - not blazing, but steadily being eaten away by Amoracchius's white fire, like newsprint slowly curling into flame. The fire didn't hide what Michael was talking about, though.

Grave Peril Chapter 5, Page 44-45


Michael started forward, the sword's white fire lighting the night like a halogen torch. The Nightmare screamed in fury and threw itself to one side, avoiding the blade, then rushed back in toward Michael, fingers raking like claws. Michael ducked under them, planted a shoulder in the thing's gut, and shoved it away, spun, and whipped the sword at it. Amoracchius cut into the Nightmare's midsection, and white fire erupted from the wound.

Grave Peril Chapter 21, Page 207