Murphy illusion

“Uh,” Butters said. “Point of order? There’s a locked door and a bunch of guys with guns between here and there.”
Molly stood up. “They won’t have guns,” she said calmly.
Butters frowned. “Uh. Dresden just said . . .”
“I heard him,” Molly replied. “They’re going to empty their weapons at you the moment they see you in the doorway.”
“Okay. As plans go, I can’t be the only one who has a problem with that,” Butters said.
“Illusion?” I asked Molly.
She nodded.
Murphy frowned. “I don’t get it. Why that? Why not push them back with fire or make them all go to sleep or something?”
“Because this is the bad guys’ home,” I said. “They have a threshold.”
Molly nodded. “Any spell that goes through gets degraded down to nothing. I can’t push anything past the door. If I go in without being invited, I won’t have any magic to speak of. Without an invitation, Harry can’t cross the threshold at all.”
Murphy nodded. “So you’re going to give them a target at the door. Makes sense.” She frowned. “How were you going to get back in, Harry?”

Ghost Story Chapter 46, Page 479-480


When the dust cleared enough to see through, the door swung freely on its hinges. Murphy stuck her foot around the corner and kicked it all the way open, then gestured to Molly.
Molly murmured and closed her eyes, then lifted her hand. Abruptly, there were two Murphys crouched by the door. The one nearest it was chewing gum. Noisily. She stood up with her P-90, flicked on the little flashlight under the barrel, and stepped around the corner, the gun pointing down the stairs.
Gunfire erupted. The gum-chewing Murphy dropped to one knee and started shooting, the assault rifle chattering in two- and three-round bursts. It was noisy as hell for about five seconds, and then there was silence. Gum-chewing Murphy withdrew back around the corner. Once she was out of sight of whoever was inside, she vanished.
The real Murphy stood up then and pitched an object down the stairs. A moment later, there was an eye-searing flash of light and thunder.
“Go, go, go!” Murphy called, and swung to point her gun down the stairs with just a portion of her upper body and face exposed to possible fire, while the rest of her body was hidden behind the wall. The three wolves rose and plunged through the dusty doorway in a single blur of motion.

Ghost Story Chapter 46, Page 482