Ohn is an individual who accompanied Mortarium and his son, Onan, and several other men, in Tirannwn. According to his diary, they were being tracked down by clans of the elves, and have escaped to the Poison Waste, south of modern-day Tyras Camp.
Upon their arrival, they encounter Harcinqa, her mother, and her brother Rentos, who traveled here from Arposandra. Deciding to temporary settle in with them, they encounter Zulrah, a giant serpent, who ate five of Ohn's men before awakening.
The next day, Harcinqa's mother assured them of a plan that will lure the serpent out. The plan turned out to be sacrificing Rentos, her son, to Zulrah in order to create a contract between it and the people accompanying her. She would bring it regular sacrifices, even going so far as to worship it as their god. Agreeing on the deal, the serpent retreated into the swamps.
As the men finally manage to catch some eels, Harcinqa's mother believes it is Zulrah's doing; it sends them eels, and in return they send it sacrifices. She names the snake Zulrah and calls herself the High Priestess of Zulrah. According to his diary, it is presumed he was chosen as a sacrifice to Zulrah and perished.