I finished this beast for its pre-release in AFS Magazine (noted in another thread) issue #2. The article weighed in just short of 1,000 words. Here's a teaser description:
"...There is only one ancient source that mentions these beings: Reflections from the Black Pool by Nym Slevvus. Relevant text from volume #4 of that 22 volume set states:
…“There are many hidden realms. Several of these correspond to the corners, or cracks, of planes that gods of this dimension cannot fathom. Much escapes through these apertures that cannot again reenter them. Some are creatures with forms recognizable by us of similar make; others, like those that the great Loz-Toron described before his demise, are as alien to us as we are to them.
“One such manifestation is a bright cloud of whirling ice and dust; and as encountered by the Me-goh who thereafter named these the N’Ifsh’isk-X’yna, which roughly translates to “The cold-light sky gas.” As there is no direct corollary for this symbolic description in any of our languages, its transliteration is hereafter ascribed, for purposes of clarity, to a rare cloud formation occurring in northern climes. This anomaly is surprisingly common to those nomads dwelling in the Land of Ebon Ice where it is referred to as muyoss, or, ‘fierce cloud’.”…
Ahem. Well yes. It was used BitD (but as revised here) in the story arc I created (referenced earlier and as will be noted in the accompanying article in AFS#2). These creatures were summoned by priests and mages of the LDEO, so that might provide a clue.