Changing the spell in the Ring of Counterspells

[Adjoint]

Ultimate Equipment, p. 168 wrote:

Upon first examination, this ring seems to be a ring of spell storing. However, while it allows a single spell of 1st through 6th level to be cast into it, that spell cannot be cast out of the ring again. Instead, should that spell ever be cast upon the wearer, the spell is immediately countered, as a counterspell action, requiring no action (or even knowledge) on the wearer’s part. Once so used, the spell cast within the ring is gone. A new spell (or the same one as before) may be placed into it again.

If there's a spell already stored within a Ring of Counterspells, is there a way to replace it with another spell without first discharging old spell by casting an appropriate spell on the wearer?

[Adjoint]

The specific situation I have in mind is: the PCs defeated a demon (succubus) who was wearing a ring of counterspells with dismissal spell in it. Of course, none of the PCs is an extraplanar outsider, so this is useless to them. Additionaly, none of them can cast dismissal spell. Therefore my question is

Is there a way to empty the ring without casting dismissal?

The way I came up with since the first post is to use dispel magic (treating dismissal as an ongoing spell affecting the ring of counterspells). Would it work?

[Dreikaiserbund]

I suspect this is too narrow for there to be a ruling, honestly. Past that...

Were I the GM, I'd just let the PCs empty the thing automatically and put in whatever spell they need. This lets them actually 'use' the loot they already earned (unless the whole point of the Dismissal was to keep the PCs from benefiting from the Ring of Counterspells, in which case we enter sticky territory).

If the GM is a stickler... best bet is to go to some town and hire a spellcaster to cast Dismissal. It's only a 4th level spell and on the cleric list, so most small towns and bigger will have someone who can cast it.

[GM Rednal]

I, too, would simply let the PCs change the spell inside the ring at any point in time, effectively overwriting the previous spell.

[Adjoint]

I'm using a module, and I believe the point of the ring containing dismissal is because the succubus was prepared for the case if someone wanted to dismis her. Even if none of the PCs know the spell, they could have bought a scroll, so I kept it as it was. But then I started wondering how are they going to make the ring useful.

I was thinking of homeruling it like you say, that it can be emptied by the wearer at will, or maybe that the spell stored can be removed with dispel magic, but I wanted to know if there's an already established way of doing that.

[GM Rednal]

Specifically as written? Not that I can recall. Dispel Magic is ideal if you want a minor cost associated with changing the spell (one of the players' spells per day, or bought as a service, plus the spell they want to put inside it), and it has the benefit of being thematically appropriate for this sort of thing.

[Pizza Lord]

It's not useless to a PC. Dismissal affects 'extraplanar creatures', not 'extraplanar outsiders'. PCs on other planes (other than transitive planes like Ethereal, Shadow, or Astral,) are actually considered (extraplanar) while there. So if they're raiding the Abyss, a demon could theoretically banish or dismiss them from the world. So it's still a valid defense, especially since dismissal has a 20% chance to send you to a plane less receptive to you than your home plane is likely to be.

Now, I don't know whether the module you are using will ever take them to such a place or encounter a foe that can cast dismissal but the basis is still sound.