Pyromancy 7

Halfway down the hall, on a broad stair that reached high into the levels above, Liliana crouched upon the steps, peering upward through a haze of smoke. Soot and ash coated her face, the vest that had once covered her tunic was nothing but cinders, and she held her burned right arm close to her chest. Black energy flowed and crackled around her, the lingering remnants of what had been a potent necromantic aura. Above, Baltrice sneered down from behind a shield of crystalline, rock-hard fire.

...

But neither was Liliana finished. As she peered through the smoke, watching Baltrice's fire-shield crack and split in preparation for blasting another lance of flame her way, she whispered a litany of names, twisted her fingers in impossible patterns. She thought back to what she had seen of the mechanical monstrosity that Baltrice and Tezzeret called home.

Agents of Artifice (Magic The Gathering: Planeswalker Book 1), Chapter 31