So aether, how does it work exactly?

[Enkidoh]

Right, in fact, the Twelve actually demonstrate this: each member of the pantheon has an elemental affinity, but because there are only six elements and... well... twelve gods/goddesses, it's obvious that each element is shared. Accordingly, of each divine elemental 'pair', one is umbral aligned, the other astral. An example is the two fire aligned members of the Twelve: Azeyma and Nald'thal. Azeyma is astral fire, while Nald'thal is umbral fire, which makes sense, given Azeyma is the goddess of the sun and thus is in the 'heavens' (thus, sunlight), whereas Nald'thal is (among other things), the god of the underworld, and thus, darkness or at least a more earthly 'light' (like the fire from lava). Both are fire signs, but very different aspects of fire/heat.

Thus in the elemental wheel astral and umbral are rather like extremes on a pendulum, each element can shift to either polarity and are not necessarily restricted to being solely aspected to one or the other.

Yes I know there are technically thirteen members of the 'Twelve', given that Nald'thal is technically two separate gods counted as one, but for simplicity's sake there are twelve in the... um.. 'Twelve'.