A member of the Stewards of the Vault.
Entered the Mysterium with Elder Lythiin, Stazi, Stanhope, Tharivol, and Nheb on 23 Pharast, 4719, in pursuit of Count Lowls and Miacknian Mun.
Survived the assault by Hounds of Tindalos on the University Level, but only barely.
On the second level, Brother Arzin managed to avoid many of the roaming dangers on the floor by Dimension Door-ing directly to the valve gate with Elder Lythiin and Sister Faria, but his sanity seemed to begin snapping by the time Stazi and Tharivol reached the Menagerie.
He was left behind by Stazi and Tharivol in Act IV Interlude Part 6 when they went to the Cipher Obscura and their deaths.
The party discovered his corpse on the Arcana level of the Mysterium in Chapter 178, lying on the floor at the threshold of the Menagerie. Found beaten to death and his corpse oddly thin, as if it had been drained of something physical. Likely slain by the Spawn of Yog-Sothoth.
First Reference: Act IV Interlude Part 2
Other Notable References: Act IV Interlude Part 3, Act IV Interlude Part 4, Act IV Interlude Part 5, Act IV Interlude Part 6, Chapter 178