Mist

The Queen of Air and Darkness cast back her head, her eyes going wild, her smile widening to inhuman proportions. “The numbers stand at one Mab to none. That advantage shall be sufficient.”
Suddenly I was aware of the creatures of Winter beneath my command, racing to join us. The temperature around us abruptly plummeted. White winter frost began to crackle across the face of the Bean, and Mab shuddered and arched her back, her eyes closing, as the breath of Winter itself gathered around us. White mist began to thicken the grey haze of the city. The air suddenly became close, intimate, as the cloud of cold vapor enveloped the cohort.
The faemetal weapons of the Sidhe began to creak and moan as deathly frost formed upon them.
And I realized that I could suddenly see no farther than maybe fifteen feet, tops.
“We won’t be able to see them coming,” I said in a low voice.
“Irrelevant,” Mab replied.

Battle Ground Chapter 27, Page 246