The Astral Empire: Travel, Part 2

(Disclaimer: the Abh are ultimately the work of Hiroyuki Morioka. This adaptation to the fourth edition of Dungeons and Dragons deviates significantly from the original.)

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Teleportation circles exist, but are uncommon outside Duchies. This is mostly because they cannot be created in the open Astral Sea: they must exist within the boundaries of a crystal sphere or veiled astral domain, so no asteroidal domain will have them — not even Lacmhacarh. As such, their utility is seen as somewhat limited.

Knowledge of how to perform the ritual Planar Portal is theoretically restricted to nobles; in practice, almost everyone who has the time and access to materials to become an 18th-level ritual caster is a noble anyway. (Exceptions may exist as wealthy commoners in a Duchy or Grand Duchy which has the population and legal permissiveness necessary to support a sub-noble leisure class.) Additionally, physical planar travel is cheap enough that there's little use for it save in emergencies.

The ritual Astral Sojourn, due to its inherent limitations, is not significantly restricted by the Empire; it is generally considered little more than a curiosity, as there are few ritual casters with the ability to make long-duration treks through the Astral, and in any case a sojourner cannot enter a veiled domain, nor a crystal sphere.

Note that "a random spot in the Astral Sea" is meaningless in the abstract without a distribution function, and that this matters: if it's a Gaussian with a standard deviation of three days' travel, that makes this ritual significantly more useful than the same with σ = fifty million years' travel, or worse, a point selected with equal probability density among those exactly fifty million years' travel in a random direction. If the function is one of the latter two — which are largely indistinguishable from the whim of an impermissive DM — Astral Sojourn is almost completely useless.

On the other hand, if we assume σ is between three and seven days' travel, or that the DM is sufficiently permissive to be approximated by such a Gaussian, this permits the theoretical existence of a group that can combine this ritual with, e.g., a hidden outpost within a crystal sphere, a folding astral skiff, and the Astral Guide ritual, and have interesting effects on the local Sea.

So let's go with something close to that: for the purposes of this setting, the ritual Astral Sojourn is emended by appending to the end of the first paragraph the simple clause “... within seven days' travel by an astral skiff from the crystal sphere of origin.”