The Psion power, dimensional scramble, offers a curious group teleport:
Hit: 1d6 + Intelligence modifier damage, and you teleport the target to a square adjacent to the burst.
While teleportation requires that the destination square be empty (as moves cannot be into occupied squares), there are no prohibitions against teleporting someone above someone else.
Are there any rules in place to handle people falling on other people? Is dimensional scramble a 3x3x1 zone, a 3x3x2 zone, or a 3x3x3 zone by the rules? Is it possible to iteratively drop people in the same air-based square, so that they all fall in a heap? If not, are there any rules besides common sense that prohibit it?