The document introduces "Horde Mode", a fan-made battle mission expansion for Warhammer 40,000 that simulates last stand battles. It provides rules for two opposing sides: a small "Band" facing insurmountable odds against a larger "Horde". The Band aims to damage the Horde or complete an objective, while the Horde seeks to overwhelm the Band. Rules cover army composition, special abilities, deployment, scoring, and using terrain to make dynamic games that can also craft narratives. The expansion is intended to convey desperate battles against overwhelming forces in the Warhammer 40k universe.