Running along much of Mendev's southern border with Numeria, the Egelsee River is an important geographical feature for Mendev.
Bounty of the river
The river provides the capital city of Nerosyan with all of its fresh water, and the abundant fisheries found along the Egelsee's length help keep Nerosyan's population fed. Despite this, the most important feature of the river is a unique mineral that collects in its silt called Nexavar. This mineral counteracts the corrupting influence of the Worldwound, meaning that the southern length of the Sellen River is not corrupted by demonic influence and that no aquatic demons can swim down its length to the lands it touches, or even worse, the Inner Sea. If it was not for the Egelsee River, who knows how far the demonic taint could have spread. Nexavar is so effective at stopping corruption that it was used in the creation of the Wardstones that help keep the expanding Worldwound in check.
Numerian raids across the Egelsee used to be quite common, but the increasing presence of crusaders in Mendev has deterred these attacks in the past few decades.