Dark seepages first appeared during LU46 as part of the lead-in to The Shadow Odyssey, and they disappeared when that expansion went live. Years later, a few dark seepages were encountered during a specific quest in the Vesspyr Isles.
"Dark seepage" is the correct name - unlike many other SOE monsters their name does not contain 'a'.
- dark seepage (Void Tempests) - spawned in various zones during the lead-in to The Shadow Odyssey, no longer in-game
- dark seepage (Vesspyr Isles)