E6M2 (aka The Water Shrine or Ruined Temple) is the second of three bonus levels in the Heretic: Shadow of the Serpent Riders expansion.
This level and episode name are in fact Untitled and can only be accessed via a warp command. According to the Heretic FAQ, a map creator by the name of Sailor Scout came up with the name Fate's Path for the episode name and The Water Shrine for the map name. The wHeretic source port offers this "episode" on the main menu using the names Sailor Scout assigned (although the automap shows the map title as "Water Shrine" without the leading article). In an interview with Michael Raymond-Judy of Raven Software, he stated that this map was designed at least in part by Brian Raffel and it was sort of a Ruined Temple although he didn't specifically name it.
While this is not part of a true episode, completing this level will take you to E6M3.