Legends of the Ancients is a fan-created campaign for Heroes of Might and Magic V, the first part of which was released in October of 2006. It takes place in the original Might and Magic universe, and takes place after Heroes of Might and Magic IV in the world of Axeoth. There were originally supposed to be four campaigns, or "Books", but only three of them were released so far (the 3rd part after an over decade-long break).
The campaigns were created by Julien Pirou, who later became a Ubisoft employee and worked on Might & Magic: Heroes VI, Might & Magic X: Legacy, and Might & Magic: Heroes VII. Artwork for the campaigns was created by Jean-Mathias Xavier. The official website for Legends of the Ancients is www.lota.celestialheavens.com/.
The story involves Malustar taking control of the Kreegans and waging war against their former ally, King Gauldoth Half-Dead of Nekross. In Great Arcan, Gavin Magnus wakes up from his coma and tries to stir up conflict between Great Arcan and their neighbors in Palaedra. And as the elves of Aranorn expand their borders, they come into contact with their relatives, the dark elves of Axeoth.
Book 3 was released in February, 2019.
While Book 4 of the campaign remains unfinished, the complete story is available in PDF format.