Phantasmagoria

By means of this spell, the illusionist prepares a special form of spectral forces spell which is triggered by some special action. 

The phantasmagoria typically includes a full visual, audial, olfactory, and touch illusion which involves falling, sliding, or moving rapidly. The effect can be aimed at making the subjects believe that they are so doing or that something else is doing so. 

For example, the phantasmagoria may be triggered when falling into a pit, reaching the center of an area, opening a door, or performing some like action. The subject(s) will then believe that the fall continues for scores of feet; that a pit has opened and that they are helplessly sliding down into an unknown area; that a wall of water is rushing down from the area beyond the just-opened door, or whatever. 

Note that unlike the programmed illusion spell, the phantasmagoria spell must always involve the illusion of something falling or rushing, or a dwindling perspective.