This spell creates a two-dimensional magical field on one side of the caster of any size up to 18' x 18'. When viewed from one side (caster's choice), this field of magic is not visible. When viewed from the other side, it will display an illusion of the space beyond perfectly, filtering out the caster and/or any creatures of the caster's choosing.
Other than its magical nature and illusory effect, the wall has no effect on anything around it. Objects, creatures, and spirits can pass through it entirely unhindered.