McGuffin to stop extraplanar invasion needed

[MarkVIIIMarc]

Hello, Insider the Tomb of Horrors I would like to place a McGuffin to stop an extraplanar invasion by a group of Mind Flayers but I can't quite decide on a name or the mechanics of it. I've had everything from the Red Dust of "V" to amulets which need attuned to which shut down psionics on a ridiculous scale come to mind.

Bonus if it has a limited time of use like the life span of the PC who is attuned to it.

My party isn't above slight cheese either but a solar powered MP3 player with only Back Street Boyz songs on it probably won't do lol.

Thanks in advance for any ideas.

[Kane0]

Maybe an anti-tuning fork? Planeshift requires a special tuning fork keyed to the plane in question so have your mcguffin change the plane they are keyed to or maybe even reverse it.

Wouldn’t help with gate though, that just uses boring diamonds.

[Unoriginal]

Hello, Insider the Tomb of Horrors I would like to place a McGuffin to stop an extraplanar invasion by a group of Mind Flayers but I can't quite decide on a name or the mechanics of it. I've had everything from the Red Dust of "V" to amulets which need attuned to which shut down psionics on a ridiculous scale come to mind.

Bonus if it has a limited time of use like the life span of the PC who is attuned to it.

My party isn't above slight cheese either but a solar powered MP3 player with only Back Street Boyz songs on it probably won't do lol.

Thanks in advance for any ideas.

How about a Treaty agreed on by the different gods to stop planar invasions on this world, which Acerarak hooked into some kind of Inverting Engine to *forbid* divine interventions against such invasions?

So the PCs needs to recover the treaty to Reverse the Polarity of the Neutral Flow.

[Keravath]

Staff of Loki?

Considering you are creating the adventure then anything goes and any metaphysical thing you make up will do.

An artifact which when activated causes the fundamental "frequency" of the plane it is on to fluctuate randomly by a small amount. This prevents any new planar gates from being established but doesn't interfere with existing ones. If you want you could have a side effect that wild magic becomes more common due these fundamental fluctuations in the weave. You could also decide that the fluctuations are so small that they have no macroscopic effects except for making it impossible to "lock on" to this plane when trying to open a planar gate to it.

Depending on how you want to imagine your metaphysics you could have it block both incoming and outgoing planar gates or rifts.

[1Pirate]

One kind of Yugoloth from MToF(I think it's called a Canoloth) has an ability that prevents teleportation and interdimensional travel.
The PCs make a contract with a very powerful Canoloth who's able use the ability with expanded range against the Mind Flayers.
Because it's a Yugoloth it'll uphold it's contract.

That is, until it gets a better offer...

[Lvl 2 Expert]

Pictures of the boss Mind Flayer in a hotel room with 3 young friends and oh wow what are they doing? It gets worse, look at this one! Oh man, that's just embarrassing.

[MarkVIIIMarc]

Thank you all very much! I'm imagining a ritual involving a metal staff of Loki and a Canoloth! This should take about two sessions to play out. I'll try to remember to come back and let you know how it goes.