Clouds swirled mysteriously overhead.
At the bottom of the aisle (still high above the ground), a small platform extended out a few feet, with greatly increased visibility. On the platform I found a collection of wood pieces bolted together, such that the whole thing could be unfolded into a fairly long beam of sorts. Although it appeared to be intended to allow someone to stand even further out than the platform, it was clear it wouldn't support a person's weight, so I forbade the use of it. (On further investigation, it could't even support its own weight, as if it were cardboard rather than wood. A trap?)
In pairs, one pair at a time, we ran down the aisle to the platform. The lower of the pair (as if the aisle were split into two slightly different heights, or else half of the participants were very short) would be slightly ahead and watching for surprises; the higher of the pair would immediately cast his or her spell as soon as he made it down there.
Later I noticed that most of the time, both of the pair cast a spell; someone explained that the half-the-pair-is-a-lookout thing was just for beginners.
We were back in the real world, roughly the same group of us, walking down a wide hall. Someone came up to us and said he'd take us on a shortcut to the place, so we followed him through an "authorized personnel only" door, down a corridor, through an open hatch, down another corridor, and then to...
We were back on the phantom plane. We went through the whole same rigamarole again.
We were back in the real world, walking dow a wide hall. Someone came up to us and said he'd take us on a shortcut to the place, so we followed him through an "authorized personnel only" door, down a corridor; he asked one of our group to hit the "add" button on the panel by the hatch, and then the hatch opened. Then he saw someone coming out of the doorway where we were going so he stopped by the water cooler and started acting nonchalant. I looked around and could see a number of people working in cubicles--a crossover from another dream, I think, one of the people was a developer and the other three were QA, although I think the three were all based on real live people, at least I identified them as such at the time (but I only recall one now).
We were back on the phantom plane. There were two people sitting in the front row, seemingly mocking us. I went up and stuck my possessions on the ground in the second row on the opposite side of the aisle from them. I spread out a small blanket or rug, trying to be careful to make sure that if anyone teleported onto it they wouldn't end up inside one of the chairs. I also arranged some other stuff I don't recall.
Then I moved back and sat down on the other side. I was watching the various going ons of everyone still in the aisle, when I got the sense of a presence amongst them, a presence that didn't belong; a sort of faint darkness or blurriness. Suddenly, someone there keeled over dead. The presence disappeared. Then everyone was looking at me--no, past me. I turned around and saw that an inky blackness was consuming the clouds, slowly moving across the sky towards us.
Then we were in another world, next to a sort of hut. A person we really needed for his special abilities was dead, crushed under a falling wall. Our leader cast some sort of vampiric spell which would animate a skeleton a put a little glowing icon in space next to him--but the corpse was so badly mangled that the skeleton didn't even get put together right--it had a skeleton leg sticking out of its skeleton chest. It turned out, though, that the skeleton did still have the magic ability we needed to make use of.
I talked to my mentor about the consuming blackness, but s/he explained that it was happening on all the phantom planes, not just the last one we'd visited--the six phantom planes formed the faces of a cube (you could tell sort of 'cause the clouds moved differently on the planes that contained the "poles"), and the creeping black void was crossing from one plane to the other