Forcecage

This powerful spell enables the caster to bring into being a cube of force, but it is unlike the magical item of that name in one important respect; The forcecage does not have solid walls of force; it has alternating bands of force with 1/2-inch gaps between.

Thus, it is truly a cage rather than an enclosed space with solid walls. Creatures within the area of effect of the spell are caught and contained unless they are able to pass through the openings—and of course all spells and breath weapons can pass through the gaps in the bars of force of the forcecage.

A creature with magic resistance has a single attempt to pass through the walls of the cage. If the resistance check is successful, the creature escapes. If it fails, then the creature is caged. Note that a successful check does not destroy the cage, nor does it enable other creatures (save familiars) to flee with the escaping creature. The forcecage is also unlike the solid-walled protective device, cube of force, in that it can be gotten rid of only by means of a dispel magic spell or by the expiration of the spell.

By means of special preparation at the time of memorization, a forcecage spell can be altered to a forcecube spell. The cube created is 10 feet on a side, and the spell then resembles that of a cube of force in all respects save that of the differences between a cast spell and the magic of a device, including the methods of defeating its power.

Although the actual casting of either application of the spell requires no material component, the study required to commit it to memory does demand that the wizard powder a diamond of at least 1,000 gp value, using the diamond dust to trace the outlines of the cage or cube he desires to create via spellcasting at some later time. Thus, in memorization, the diamond dust is employed and expended, for upon completion of study, the wizard must then toss the dust into the air and it will disappear.

[Player's Handbook]

School: Evocation
Level: 7
Rarity: Common

Range: 10 yards per 2 levels
Components: V, S + special
Duration: 6 turns + 1/level
Casting Time: 3-4
Area of Effect: 20-foot cube
Saving Throw: None

Material Components: powdered diamond of at least 1,000 gp value (see description)