"Yes, you can get to other planets and in theory even other stars by travelling - up, until there's no air, and then in whatever direction you wanted to go. But it's an unimaginably long way. Actual interplanetary travel happens via portals or Interplanetary Teleport and we can see if Fazil's routing through the elemental planes thing works."

Vanyel looks thoughtful for a while. 

"...All right, I'm not sure that gives us much lead, other than 'some kind of Aucturn magic'. I suppose we can try the door and teleport or Gate out right away if it's more than we can handle?" 

"And send in some critters first, yeah."

"Of course." Vanyel starts examining the spells on the door; are they significantly different from the other doors? 

They're quite different and, after a bit of looking, simpler. The door is locked with magic, and the lock is intertwined with eleven different lightning bolts, and the room doesn't actually seem shielded against Farseeing but Farseeing claims that there's nothing at all on the door's other side. 

Vanyel describes this to the others. "I'm pretty suspicious, though, I think there's something weird going on here. Hmm. Is it possible the contents of the room are in some sort of extraplanar space, like the cargo bag? I don't know if that makes sense, but I'm pretty sure it's tricking my Farsight somehow." 

"Wizards can build their own permanent demiplane, he might've done that."

"What would that mean for the defences, if he'd done that?" 

" - you can change how time passes, on a personal demiplane. You can change whether magic works - I guess it'd be pretty secure to just make a personal demiplane where magic didn't work but I'd expect it to be kind of maddening, for a wizard - if he found a way to make magic only work for him, no one has since. 

I think we are definitely safe if we don't go into it but it would not be hard to make us regret it if we do."

"Is this something where my kind of magic would help? Maybe if we get the door open, I could see in with mage-sight or Farsight without actually going in..." 

"Maybe. He won't have specifically thought to protect against it, at least, I'd expect."

"All right, I'll have a go at unlocking this door. You all should stand back and we can get the dogs closer again?" 

They can do this.

And Vanyel will try to snip out the interlocked lightning bolts without any spells actually firing, but failing that at least be standing thirty paces back, have lots of shields up, and have the dogs closer than he is.

He's getting pretty good at dismantling interwoven lightning bolts; he can get them all. 

Aaaaaand have Mahdi's Unseen Servant open the door for them? Probably Fazil should cast Delay Pain so Vanyel can be ready to Gate them out instantly if anything happens, and - hmm, he's wondering if Mahdi can command his Unseen Servant to head for the door right before all of them duck into one of the already cleared (and shielded) rooms, with the door shut? He should test whether Farsight or mage-scrying can see out of it, though, since he'll want to check what's going on.

Fazil can cast Delay Pain and Mahdi can have the Unseen Servant wait to open the door until they're in a cleared room that doesn't block Vanyel's senses.

The Unseen Servant opens the door. Beyond it is - a stunning view of the stars.

"...Is it opening into the void between worlds." 

He can try to check, by extending his Farsight viewpoint out past the threshold? 

"The void between worlds doesn't have air," Mahdi says, "and air goes places where there isn't air, we'd have heard hissing."

He can extend his Farsight viewpoint to the threshold but it abruptly stops working once it crosses it.

"There's some sort of discontinuity at the doorway, I can't Farsee past it." Do the stars look like anything to mage-sight? Can his Thoughtsensing get past the threshold? 

Nothing in the room looks like anything to mage-sight. Thoughtsensing is not allowed in either.

"I can send the Unseen Servant but I bet anything it winks out at the threshold."

"This is really not inclining me to go in there!" Sigh. "Is there anything non-magical we can send in? Probably not." 

"- well, there's Fy -"