Patrons walking down a long hallway suddenly see an witch/actor running toward them. Right before she runs into them she disappears and blast of cold air is felt in the patron's faces. The witch will them reappear behind them, cackling hysterically.
As the witch/actor is about to collide with the first patron, a strobe can fire as she ducks into a side cubby-hole. At the same time, a fan can blow a blast of cold air through tubes mounted on the walls. These tubes would work similar to a homemade device for chilling fog machine fog for a better ground effect. You'll need ice and/or dry ice to chill the metal vent pipes. A second actor costumed the same as the first, can then appear from another cubby-hole hole behind the patrons.
- For the chilled air effect, it is probably more important to be cold than to produce a big windy effect.
- To avoid accidental collisions between actor and patrons, the hallway could contain some divider mechanism so that they never actually meet. In this case, there would be a side exit from the hallway at the point where this divider is set up.