Skirmisher Publishing has released more than just an encounter or an adventure, they've released a self-contained campaign-length book for 5th Edition. It's At the Shrine of Othrys and you can purchase and download your copy now.
From the website
“You have travelled through a desolate wilderness and, after braving untold hardships and dangers, reached the base of Mount Othrys, legendary headquarters of the Titans during their war with the Olympian gods. Before you the valley widens out and, at its center, is a small, rugged hill, a ring of large standing stones at its top marking it as a place of worship since the earliest times. On the western side of this mound of rock, the Rematia River expands into a small lake, and on the eastern side a plume of smoke rises from the ground between it and the mountain. Scrubby copses of vegetation cling to the base of the hill, and sparse rolling grassland lies in the quarter of a mile that separates you from it. You know that you have surely arrived at the Shrine of Othrys.”
“At the Shrine of Othrys” is a self-standing, campaign-length 5th Edition adventure designed for a party of four or five 1st-level characters and intended to take them to at least 5th level and to lay the groundwork for continuing scenarios and advancement. This 118-page sourcebook includes:
● A complete, detailed, five-part dungeon, along with history and background of the site and notes on how to run the adventure;
● Descriptions and stat blocks for 63 monsters, including 24 Mephits, six Special Monsters, three Titanic Clergy, 18 Humanoids and Soldiery, and 12 members of the Cult of the Fish-Born;
● An Encounter Table for the region around Mount Othrys that allows for sandbox play;
● Four ready-to-use Pregenerated Characters.
● More than 70 illustrations by artists Bob Greyvenstein, Amanda Kahl, and Brenda Cass;
● Four maps by cartographers Amanda Kahl, Octavius Knorr, and Art Gowie; and,
● Guidelines on concluding and continuing the adventure.
This scenario is was developed for use in Skirmisher Publishing’s bestselling Swords of Kos Fantasy Campaign Setting and highlights some of the themes and tensions associated with it. It is, however, suitable for use in any traditional milieu, and the dungeon and even the wilderness area surrounding it can be easily dropped anywhere appropriate in a storyteller’s own world. It is fully supported with free supplemental material on a dedicated “At the Shrine of Othrys” Bonus Content page at d-Infinity Online game magazine.