D&D 5E Cube of Force Conundrum

[CM]

An issue has come up in my campaign regarding the Cube of Force's 4th function: "Spell effects can't pass through the barrier."

First, everyone in the group agrees that in this mode, the cube prevents spells from taking effect on creatures on the opposite side of its barrier. So someone inside the cube who attempted to bless or friends creatures on the outside would be unable to affect them, likewise someone on the outside who threw a fireball at the cube would see it explode on impact with the cube's surface (leaving cube occupants unaffected). Attempting to teleport to the other side of the cube would fail.

The point of contention is existing spells.

I believe that if someone with an active spell crossed the cube (in either direction), the ongoing enchantment would be unaffected. Bless, fly, charm person, confusion would continue to work as normal.

Another member of the group believes that any spells affecting someone who entered the cube would be suppressed (though duration would continue to run) while they are inside it. This would included someone who started their turn inside the cube, moved outside it, and then went back inside: they would find their ongoing spells suppressed.

I suggested that you could then use the cube offensively to move up to someone and suspend all their ongoing spells, or negate permanent spell effects temporarily, but we agreed that would be overpowered and not in the spirit of the cube. I also think that if were intended to suppress effects, there would be some reference to the antimagic field spell in the PHB, as it has extensive rules for suppression of effects.

What do you think?

 

[Warmaster Horus]

My first impression is that the Cube of Force's magic suppression is akin to a Globe of Invulnerability but for all spell/magical effects. So magic cast inside/outside cannot effect targets on the other side nor can the area within the barrier be effected by spells outside the barrier. Existing (concentration) spells cast inside/outside can transition the barrier freely.

 

[Yunru]

Sounds pretty simple. Spell effects can't pass, so they end.

 

[mellored]

Running into a lead lined room buried 100' down on anoyher plane of exsistance doesn't stop a spell already in effect. I don't see why a force cube would either. It's a strong enough spell without also being a disenchant.

But really, whichever is more fun.

 

[Tony Vargas]

Another possibility: the subject of an ongoing spell effect cannot pass through the barrier in question.

 

[Kalshane]

The point of the spell is there's no line of effect to anyone on the other side of the wall. It doesn't dispel existing effects (if it did, that would be specifically spelled out in the spell description.)

 

[Tony Vargas]

Sounds pretty simple. Spell effects can't pass, so they end.

Reasonable, at least, in the case of a creature crossing the barrier.

I suggested that you could then use the cube offensively to move up to someone and suspend all their ongoing spells, or negate permanent spell effects temporarily, but we agreed that would be overpowered and not in the spirit of the cube.

In either case, if you interpret 'can't cross the barrier' as stopping movement rather than suppressing, that'd reduce the 'offensive' use - you couldn't force a creature or object under a spell effect through the barrier.

 

[bganon]

I think I'd make a mixed ruling, partly based on the paragraph that specifically forbids using the other cube abilities offensively.

For example, suppose the cube's 4th function is active, and there's a magically invisible monster. The monster can pass through the barrier of its own volition, but the invisibility won't, so I'd rule it suppressed. But I would also rule that the user of the cube can't themselves move the barrier past a spell effect (on a solid object), so if they try to approach the monster on their own turn they'd be stopped once the barrier touches the monster.

 

[Oofta]

The point of the spell is there's no line of effect to anyone on the other side of the wall. It doesn't dispel existing effects (if it did, that would be specifically spelled out in the spell description.)

I agree with this. Unless it specifies otherwise, you don't even need to be on the same plane of existence to maintain a spell.

 

[Shiroiken]

While I can see an argument that anyone who passes through the barrier has all spell effects ended, I'm pretty sure that's not RAI. DMs may choose any way they wish, of course