[RPG] How could one defeat a pervasive antimagic field

An existing forcecage spell's effect is probably unaffected by an incoming antimagic field spell's effect

A spell that creates multiple walls of force—like the the 4th-level Sor/Wiz spell force chest [evoc] (Spell Compendium 97) or the 7th-level Sor/Wiz spell forcecage [evoc] (PH 233)—requires using the rules for the 5th-level Sor/Wiz spell wall of force [evoc] (PH 298-9), and those include how the wall of force spell's effect interacts with the effect of the 6th-level Sor/Wiz spell antimagic field [abjur] (PH 200), this despite the antimagic field spell's description specifying only the spell wall of force.

The spell forcecage says

Like a wall of force spell, a forcecage resists dispel magic, but it is vulnerable to a disintegrate spell, and it can be destroyed by a sphere of annihilation or a rod of cancellation.

Compare that with the spell wall of force, which says that it's effect

is unaffected by most spells, including dispel magic. However, disintegrate immediately destroys it, as does a rod of cancellation, a sphere of annihilation, or a Mordenkainen’s disjunction spell.

The reader must refer to the spell wall of force to learn more about the spell forcecage (otherwise, for example, the phrase "vulnerable to a disintegrate spell" is meaningless). And, if trying to determine how, for example, the antimagic field spell's effect interacts with the force cage spell's effect, the reader'll end up back at the spell wall of force anyway.

It would take an extremely strict reading of the spell antimagic field—followed by a personal definition of what a forcecage spell's effect's now-mysterious walls of force were actually made of—to have an existing forcecage spell's effect suppressed by an antimagic field spell's effect.

Walls of force usually block line of effect but an antimagic field spell's effect does not

Normally, the antimagic field spell's effect just doesn't care about a magical effect that would block its line of effect: the antimagic field spell's effect causes the existing magical effect to be suppressed. But, like the spell antimagic field says—and the Rules Compendium confirms—, "A wall of force… isn’t affected by antimagic" (11).

Thus even an existing forcecage spell's barred cage effect allows spells to be cast while those within would be, if uncaged, in an antimagic field spell's effect, although usually not beyond the barred cage effect's walls. While an "otherwise solid barrier with a hole of at least 1 square foot through it does not block a spell’s line of effect" (PH 176), the forcecage spell's barred cage effect has only "half-inch wide [bars] with half-inch gaps between them."

However, casting the spell forcecage while within an existing antimagic field spell's effect and picking as the forcecage spell's effect's point of origin a crosshairs within the antimagic field spell's effect means the forcecage spell's effect is suppressed while the antimagic field spell's effect remains. (However, picking for the forcecage spell's effect's point of origin a crosshairs that's outside the antimagic field spell's effect seems to mean the forcecage spell's effect functions normally. The antimagic field spell's effect doesn't block line of effect (RC 11)—an apparent reversal of how the spell antimagic field functioned according to the Dungeons and Dragons, Third Edition FAQ—, but opinions on exactly how this works vary widely.)

There is a distinction between a spell, and a spell effect. Deities directly grant their worshipers spells, but not spell effects—the worshipers themselves still need to cast the spell, that is, finish it, to create the spell effect. Though most of the heavy lifting has been performed by a deity, the actual effect in the end is created by the worshiper, a mortal.

Thus, the effects of divine spells are subject to an antimagic field and do not function therein.

If a god came down in person to cast a spell, then that would ignore an antimagic field. So, for example, a god could cast some spell upon a mortal as a form of reward (or punishment) and that would ignore antimagic field.