I know nothing of actual black magic based on Zoroastrianism, nor would I trust the sources I have available to convey it properly. So instead I attempted to invert the basic principles of the faith as best as I could.

Zoroastrianism has a very strong focus on impeding corpses (or rather, the daemons that inhabit them after death) from corrupting the sacred elements around them, so naturally the only suitable place for black Zoroastrian magic would be a literal pile of bones. In turn, water, earth and fire should be at the center, but neglected or further defiled — this is apparent from the inversion of the usual reverent attitude of Zoroastrianism for water and fire, which are thrown on top of each other and kicked with malice.

The ripping of Ephedra over the fire is an inversion of the Thanksgiving ceremony, in which two magi exchange branches of medicinal plants, symbolizing the reaffirmation of the connection between the material and spiritual worlds. Thus, the rejection and destruction of these branches must instead mean a rejection of this connection, perhaps in preparation for the sin to be committed next: the burning of corpses. This is the greatest sin known to the faith, for which there is no atonement, as the fire is irreversibly defiled by the presence of the daemons that inhabit corpses.

Other aspects are more embarrassingly simple. Magi wear white, so these cultists must wear black. Zoroastrian rituals are still and full of chanting, so the inverse is a violent dance that takes place in silence.

In the final appendix, the Yasna is brought up. I glossed over its immense significance to Zoroastrianism in order to conserve pacing and prevent bloating the footnotes, but it still deserves further explanation.

The yasna is not only a collection of liturgical texts (which also belong to the Avesta, further divided into the Visperad, Yashts, Siroza, Nyayeshes, Gahs and Afrinagans), it is also the main act of worship of Zoroastrianism, just as one would talk about mass in catholicism. Its main purpose is to strengthen the asha: this is, that which is right, that which is created by the Ahura Mazda, and that which abides by the divine order. It is divided in 72 chapters, recited over the course of 2 hours, which are accompanied by individual ceremonies and rites (like the Ab-Zohr that is name-dropped in the article, which is the strengthening of the sacred waters and closes the Yasna).

The individual yasna verses I chose are incantations to invite the Ahura Mazda and the seven Amesha Spenta (or Bountiful Immortals) that emanate from it (which are curiously reminiscent of the seven Archons of gnosticism). This is reflected by the items each of the magi is carrying: respectively, these represent the realms of Amərətāt, Haurvatāt, Spəṇta Armaiti, Xšaθra Vairya, Aša Vahišta and Vohu Manah. The object of my bastardized ceremony (a horrendous mixture of the Sagdid and Yasna) is to summon an avatar of the final Amesha Spenta, the Spəṇta Mainyu that guards over human beings and reigns over all else.

This is done through the incantation of the Ahuna Vairya, the most sacred of all Zoroastrian prayers, which was uttered at the beginning of time by the Ahura Mazda (god-like figure) and is said to have made the Angra Mainyu (satan-like figure) flinch. The power of the Ahuna Vairya is unrivaled: it is both a potent weapon against the evil Daeva of the Angra Mainyu and a talisman to aid men in distress.

However, the magi see themselves dumbfounded by what they correctly recognize to be a direct intervention of the Moon, clearing the skies from clouds and black smoke. The moon is an important figure of the Zoroastrian cosmogony: it plays a role in saving the Gavaevodata (uniquely-created cow), one of the primordial creations of the Ahura Mazda, from death at the hands of Jahi, the consort of the Angra Mainyu, who exhorts her to do the deed.

Indeed, the bovine that destroys the feline abomination is none other than the Gavaevodata, whose identity made evident by the plants that grow from its marrow: in the original legend, numerous grains and medicinal plants are created by the death of the Gavaevodata, who laments from the Moon the attack of the Angra Mainyu upon the material world.

Other symbolism is, again, more apparent. The many creatures spawned from 009-A's miasma are other xrafstar from the Angra Mainyu, emboldened by the stench of death it radiates to kill more. The alternate world/illusion seen through the smoke is none other than the homeland of the Angra Mainyu, who lives "in a dark place." The cats flee to the North because the daemons that are dispelled through the Sagdid are said to flee there.