Eve of the Sickle Moon is an expansion to the heroic adventure game Shadowrift, a cooperative deck-building game in which the players are heroes defending a town against a horde of monsters in a high-stakes fantasy siege. This expansion adds two new monster factions:

• The Lycanthrope faction consists of were-animals in many shapes and sizes. They all bear the common theme that they're able to bite villagers and spread their curse, and that when the full moon rises they become more powerful.
• The Harrowood faction is a forest that has been twisted into a violent hatred of humanity by the opening of the Shadowrifts. They can create Overgrowths, which empower their faction and speed the town's destruction.
  

To fight back against these foes, the heroes have four new hero cards with druidic power and four new hero cards with Elementalist powers. Three new villagers and a Wall are also included.