The spell Forcecage allows you to create a prison in the shape of either a cage with bars, or a closed box.
Escaping the Forcecage is (obviously) meant to be difficult:
A creature inside the cage can't leave it by nonmagical means. If the creature tries to use teleportation or interplanar travel to leave the cage, it must first make a Charisma saving throw. On a success, the creature can use that magic to exit the cage. On a failure, the creature can't exit the cage and wastes the use of the spell or effect. The cage also extends into the Ethereal Plane, blocking ethereal travel.
However, if you choose the cage shape, it is ridiculously easy to escape, using one of the following means:
- Wildshape into an form that can squeeze through 1/2 inch gaps
- Polymorph, True Polymorph, Mass Polymorph, Shapechange or Animal Shapes, similar to Wildshape
- Gaseous Form, can squeeze through any gap. Maybe also Wind Walk, but that spell doesn't explicitly mention being able to squeeze through gaps.
- Antimagic Field: Forcecage is only immune to Dispel Magic, not Antimagic Field. Would also work on a box-shaped Forcecage.
- Disintegrate, which can destroy creations of magical force. Would also work on a box-shaped Forcecage.
- Casting Misty Step a bunch of times, since it's just a 2nd-level-spell and you're likely to suceed on the Charisma save eventually.
So, in the end, Forcecage with its cage shape seems like it's most likely a waste when used on a caster, especially a druid. Do note that Antimagic Field and Disintegrate are included not because they are especially easy, but for completeness, and to illustrate the wide variety of ways that one can escape a cage-Forcecage.
Is escaping from it really as ridiculously easy as it seems? Or am I missing something?
Best Answer
It's not easy, but you can escape quickly if you have the right tools.
The phrase "a creature inside the cage can't leave it by nonmagical means" doesn't mean you can just turn yourself into a mouse/gas/etc and move out. Walking or flying are mundane movement, even if it was magic that gave you a fly speed or changed your physical size. Your method of leaving must itself be magical, which means it's basically going to be teleportation or planar travel, so you're up against the save. That excludes the "easy" methods of gaseous form or wild shape, polymorph, etc. as escape routes.
Sure, you can spam misty step to get out sooner or later, but that does require you to know the spell (and have it prepared, if that's a thing for you), and potentially burn a bunch of spell slots and waste a bunch of turns, just to escape from one spell. I don't call that "easy". Simple, if you have the proper tools at hand, but costly. (I'm making that distinction in the same sense that walking up a mountain is simple, but not easy.) There are a number of "save or suck" effects that give you another try at the save every turn, but unlike forcecage most of them don't cost you spell slots every time you try. But yes, trapping a powerful spellcaster inside a forcecage is probably not your best use of the spell.
Antimagic field is a sure-fire escape method, from inside or outside, but escaping a 7th level spell by casting a very specific 8th level spell is a very high cost indeed. You only get one 8th level spell per day, ever, so burning that merely to escape a forcecage is a hefty price -- and again, you have to have that AMF spell prepared already, or available through some other method, like a spell scroll.
Disintegrate seems like it would work in this case, whether the caster is inside or not. A forcecage is specifically a "prison composed of magical force", and disintegrate can target a "creation of magical force", so it's a valid target, and it "automatically disintegrates" a ten-foot cube out of a creation of force that's Large or larger. I can't see any reason a disintegrate spell would not work to open a hole in a forcecage. That said, again, you're defeating a 7th level spell with a specific 6th level spell, of which you only ever get 2 per day. While it's not as uncommon as an antimagic field, it's still a significant cost that the party may not have access to. There are many such pairs of spells where one can specifically counter another.