The air suddenly shook with a bellowing, damned near leonine roar. Cassius's head whipped around in time to see my dog leap from twenty feet away and hurtle forward like a grey-furred wrecking ball.

Mouse's front paws hit Cassius squarely on the sternum, and a bloodcurdling snarl exploded from the huge dog's chest as they both went down. Mouse snapped his jaws at Cassius's throat, but he had too much momentum remaining from his charge. His paws slid on the smooth floor, carrying him past Cassius before his teeth could do more than lightly rip at one shoulder.

Cassius screamed in rage, crouching, and flicked his hand at Mouse. There was a surge of dark magic, a shimmering blur, and suddenly a serpent coalesced from the shadows lying upon the gallery. It reared up for a second, and I could see the deadly outline of a cobra's hood rising a good five feet from the floor. Then the serpent launched itself at Mouse.

My dog saw it coming, sprang back from the serpent's first strike, and then leapt forward, jaws trying to latch on behind the shadow serpent's head. Lashing loops of reptilian darkness whipped into coils that tried to trap the big dog, and the pair of them rolled along the floor, each seeking to grasp and kill the other.

Cassius stared at Mouse for a second, eyes wide, and then turned to me. There was actual, literal foam at the corner of his mouth, and his face was stretched into a grotesque grimace of fury. He lurched over to my side, speaking a language I didn't recognize in a half-hysterical shriek. Then he seized my hair, jerked my head back to bare my throat, and swept the knife down toward my jugular.

Before his arm was halfway down, there was a thin, high-pitched, tinny-sounding wail. Butters threw himself onto Cassius's back, carrying them both over me and to the floor. The knife missed me entirely, and went skittering away on impact.

Cassius snarled another oath and tried to crawl for the knife. Butters tried to pull Cassius away, his face deathly pale. The little guy had all the fighting prowess of a leatherback turtle, but he got his arms and legs around Cassius's torso and clung like a wild-haired monkey.

Cassius's body may have been weakened, but he'd had more than a millennium to learn about infighting. He twisted his shoulders and then slammed the side of his head into Butters's nose with a crunching sound of impact. Butters reeled from the blow, and blood spattered his face and upper lip.

Cassius then twisted again and escaped Butters's grip. He heaved himself toward the knife.

"Butters!" I screamed, helpless to move and furious and terrified. "Don't let him get the weapon!"