You stare at the imposing grey walls, and taste the smell of all the evil locked inside. You grin a toothy foxy grin. Your form shifts demonic unbidden, and you see your breath in the cold morning air. Inside those walls are years worth of souls. Once you start feeding though, the guards and the inmates will respond. Best to have them cooling their heels, you think. The fog coming from your lips becomes more intense. Frost covers a nearby tree.
You chuckle, "The Winter Slam is going to be a real cooler." Then you open your maw impossibly wide and a great icy wind rushes forth. The prison gates quickly are frozen fast. Power lines freeze and snap, and the emergency generators kick in. The sudden cold snap you create would be worthy of Batman's Mr. Freeze, if he were real. You walk across the now frozen river toward your own personal cooler, and leap from the ground to the top of the thirty foot perimeter wall. You find an inmate alone on the ground in the courtyard. Looks like your quick freeze foiled a prison break. He is in a fetal position trying to keep warm. You can smell the reek of evil emanating from the tattooed young thug in the prison uniform. You smack your lips. He turns toward you at the sound. He leaps up shivering more from terror than the cold, and pulls his shiv on you.
URP! He disappears down a black rabbit hole while still sporting a human form.
"So many souls, so little time," you chuckle. You turn and walk toward the prison. The guard is frozen stiff. Hm, perhaps, he was escorting your snack when he froze, and that allowed the prisoner to try to make his break. You sniff the guard, only the slightest tinge of evil, and that might be from proximity. You tap his solid frozen head, and walk on.