The Metzli were an order of priests who formed a core of the Hakkari, alongside the Atal'ai. They eventually split from the Atal'ai due to differences in dogma, and departed the Temple of Atal'Hakkar. At some point in their history, they were infiltrated by Men'heva, who began to teach his doctrine on Mnesthes. Nominally Hakkari, but truly Mnesthian, the Metzli waged war on the Atal'ai at Men'heva's behest. Their war never culminated, and a stalemate formed between the two priesthoods.
Eventually, Jin'thek arrived and with the help of the Ambertree tribe, infiltrated the Temple of Atal'Hakkar. The Metzli promised to redeem Hakkar if Jin'thek helped them, and thus Jin'thek lowered the defenses of the Temple and let the Metzli invade. The Green Dragons Eranikus, Lethon and Zulastrasz destroyed the Temple and turned it into the Sunken Temple, while the Metzli killed many of the Atal'ai.
Afterwards, Jin'thek realised that the Metzi were led by Men'heva and that he had been deceived. In helping the Metzli and defeating Hakkar, Jin'thek had eliminated one of the Prophet Men'heva's greatest enemies and rivals. Jin'thek swore to someday return and liberate the Ambertree tribe from the suffering it had experienced at the hands of the pagans of Men'heva.