Hist Sap
From the OblivioWiki – your guide to everything Oblivion
Hist Sap is a potion made from Hist Trees. The trees are native to the Black Marsh, the homeland of the Argonians.
You obtain Hist Sap when doing the Blackwood Company mission "Infiltration." It causes you to teleport to the quest destination of Water's Edge, where you kill all of the goblins infesting the place. It is only later that you find all but one of the residents of Water's Edge dead, and realize that the Hist Sap made you think the residents were goblins.
