In the sidebar "Midnight Mirror Planar Traits" (p. 19) the midnight mirror is described as a "locked plane" wherein planar travel in and out is restricted to three specific options. The first option is to use a command word, the second is to switch souls with someone on the other side of the mirror, and the third is to destroy the Heart of the mirror.

Does this trait of the mirror prevent the summoner from summoning his eidolon? Do all summoning spells fail to work? If an eidolon enters the mirror via the command word, what happens if it is killed? Can such an eidolon be dismissed?

I didn't have a summoner in the party when I ran it, but I ruled that the wizard's summon monster spells failed due to the reasons you mention above.

So that's what happened to all the synthesists.

I didn't have a summoner in the party when I ran it, but I ruled that the wizard's summon monster spells failed due to the reasons you mention above.

Thanks, that's the way I'm going to rule it. Luckily the summoner brought his eidolon in with him already summoned.

Does anyone have any thoughts on what would happen to an eidolon if it is killed while in a locked plane? I think it would just fall to the ground and wouldn't be able to be resummoned until its body escaped the prison.

I believe that it would go home since it is technically a summon. That is the way summoned monsters would work if a condition came up which prevented plane travel after they had been summoned. Death or expiration of the spell does not prevent a summoned monster from returning to its native plane.

Also note....a biggy....you can not teleport! Teleporting involves travel through the astral plane and thus the entire teleportation sub-school is non-functional

I am unsure of summoning not working. This is because you are not actually bringing a creature from another plane. You are manifesting energy into the form of the creature summoned. It's a grey area as to how GMs feel it works.

I would rule that"
1) Teleportation and Calling subschools do not work.
2) Eidolon's can not be summoned, since this functions more like a calling (subject to banishment and dismissal but not dispel magic) than a summons in most regards. It also mentions that the eidolon is sent back to it's home plane when it reaches death.

Would an eidolon understand that? It depends on how you play the eidolon: is it just a vessel for the PC's will, or does it have an intelligence and personality of its own? If it's the latter, then it might make a Knowledge (planes) check and realize the situation.

I really want to allow summoners full use of their class abilities when in the Midnight Mirror, but I'm having difficulty justifying it.

The description for the summoner's eidolon says that it is treated like a summoned creature, so I feel like I can ignore the similarities they have with called creatures. I feel this way because it seems that summoned creatures can come from another plane, although it isn't necessary that they do.

For instance, summon monster describes the creatures brought by the spell as 'extraplanar'; whereas summon nature's ally describes them an 'natural'. (Does dismissal work against 'natural' creatures summoned by summon nature's ally?)

Furthermore, the eidolon is described as returning to it's home plane when it dies, so it seems very likely that it comes from that plane when it is summoned.

So in the end I may not allow summon monster spells, but I may allow spells like summon swarm and summon instrument. I don't want to, but I have no justification for not allowing summon nature's ally as they are not extraplanar creatures.

Also, teleportation definitely won't work, nor will blink.

Any thoughts?

Summon Nature's ally summons extraplanar creatures (such as elementals) also normal creatures are pulled from another plane when your not on Golarion (for example dogs dont exist in the elemental plane of fire so you have to summon one from a normal area). So either all summon spells work or none do.

Summon monster either manifests a creature that is by its nature from another plane or has a template applied to it that makes it from another plane. This is noticably different from summon nature's ally[/]. Furthermore, [i]summon monster says it summons an extraplanar creature, while summon nature's ally says it summons a natural creature. Summon monster always manifests a creature from another plane, whereas simon nature's ally can summon many creatures that are from the Material plane.

When you summon creatures from the Material plane while you are on the Material plane no planar travel is necessary. But, in the midnight mirror all of these creatures are extraplanar so I see now that summon nature's ally wouldn't work either.

The above would be true if summon subtype conjuration spells were actually using planar travel to bring the creatures to you, but this may not be the case. The description for the conjuration school of magic says that a summoning subtype spell brings a "manifestation" of a creature to you, so maybe no planar travel is necessary because you are not bringing the actual creature to you.

My question now is: Does summoning an eidolon involve planar travel or is an eidolon merely a manifestation. I think the former is true, so a summoner would not be able to summon his eidolon while in the midnight mirror.

I think I just came to the same conclusion as Lab Rat.