Aza'Methet

What it was. An ancient two-minded non-humanoid entity, second-to-last survivor of a race spawned in the "fourth great generation of being" when the physical laws of the universe were still unstable, more than three hundred generations of stars ago. Its homeworld was destroyed eons past; it now hides in a self-made prison, a crack in reality, moving on four stumpy legs under crushing gravity with a neutronium shell on its back. Its two minds war constantly (one suicidal, one survivalist), and it has been "used as a slave and worshipped as a god" by younger races ("its name had been given to it by its first cult"). In its memory-scene Minalan witnesses Aza'methet fight and consume a hunter of the Formless in a battle beyond description, involving "time and space, order and chaos, quantum physics and telepathic assault," lures made of snowstone, bludgeons of impossibly black magical obsidian, and catastrophic blasts into other realities. "I saw the secrets of their construction as he conjured them into existence." Minalan goes clinically mad under the weight of the experience, saved only by clinging to Alya as his constant, and his heart stops. Briga intervenes; Lilastien's CPR revives him. Voice: inhumanly indifferent, paranoid, contemptuous, obsessed with self-preservation. "Life is a sin, a stain on the cosmos." Unique knowledge: fundamental dimensional, quantum, and temporal magic, the secrets of snowstone construction, weapons-grade magical obsidian, the nature of the Formless, and raw power sufficient to rearrange reality.

Book 14.5 (Mad Mage): The book about Aza'methet, effectively. "There is a reason I fear Aza'Methet's presence more than all the others combined." It gives Minalan the dimensional-magic insights that underpin the portal arches that bypass the Ways entirely:

Aza'Methet knew the intricacies of dimensional magic as well as I understood color. It saw the use of the Alkan Ways as a crude, even quaint use of the complex energies and physics of the magnificently obscure subject.

Paired with Umank, it designs the archways. It also rearranges the Snowflake's internal architecture to unlock temporal manipulation, transforms Tanno Amberil (Lilastien's Acennan staff) into a tool "so intricate that I do not understand its capacities," creates permanent dimensional pockets Minalan uses thereafter, and nearly destroys Sevendor by building an impenetrable bubble that holds the duchy in a timeless stasis for two full days before Lilastien puts Minalan into a medical coma. Its arsenal knowledge is what turns Avalanche into a fundamentally different weapon:

Aza'methet really understood how to make something magically destructive.

Book 15 (Marshal Arcane): Avalanche's new offensive capabilities, the improved portal production, and Minalan's ability to summon the dead with Mel Thenreyal through the Castle Salaisus Threshold glass all rest on Aza'methet's instruction:

only Mel Thenreyal and Aza'methet had any experience with divine magic, although both of them used different terms. Of the two, Aza'methet had a more comprehensive knowledge of the subject.

Book 16 (Preceptor): One of the three "monsters" in Minalan's head. Supplies the foundational arcane-energy theory that lets him recognize divine sparks ("Even life is an unexpected result of the basic physical laws of the universe, I agreed, recalling the ancient memories of Aza-Methet. Some consider it a violation of the rules"), and Minalan consciously leans on its contributions while planning Darkfaller: "that ancient horror had some bloody brilliant ideas."

Book 17 (Practical Adept): Aza'methet's dimensional-pocket vault technology is where important artifacts are stashed and recovered, including the hoxter that houses the Junebug for its Farise debut.