Heroes of Might & Magic III: Horn of the Abyss

Will there be original campaigns in HotA?
The title is promising...

Yes, there will be. The first three versions of the add-on comprise the first three chapters of a massive campaign. Each chapter, while united by a common storyline, is primarily dedicated to specific new towns featured in these versions – the first will focus on the Cove, the second on the Fortress, and the third on the Temple. (The order is exactly as listed).