Amber Plasm is an orange sap-like substance produced by the mad Hist of Mazzatun, Tsono-Xuhil. Despite its appearance, this material is not like normal Hist Sap, and appears to be a form of chaotic creatia from Oblivion which leaks into Mundus through the Hist like blood from a wound. Amber Plasm is usually associated with Sithis. Drinking it or bathing in it causes hallucinations and serious blistering that can result in death. These effects can drive an Argonian mad. Amber Plasm has even been utilized to create "Amber Projections", phantoms of the recently deceased who are said to be "preserved in amber". These phantom forms are not exclusive to Argonians, as even dead haj mota have been summoned in this manner.
The Tree-Minder of the Xit-Xaht tribe once attempted to harness Amber Plasm to achieve great power and order. Through alchemical study and the Tsono-Xuhil's guidance, Tree-Minder Na-Kesh of the Xit-Xaht learned to harness the power of the substance. When properly manipulated, amber plasm can grant a Saxhleel great speed and strength. She performed horrific alchemical experiments on the substance, and planned to use it to uplift her people and return Black Marsh to the pre-Duskfall way of life before conquering all of Tamriel. This dangerous alchemy was stopped by a group of Undaunted circa 2E 582, who killed Na-Kesh and liberated the enslaved Su-Zahleel tribe from Mazzatun. The surviving Su-Zahleel elders then put the mad Hist into a deep slumber, hoping to alleviate its madness.