The Tear of Asha is an artifact in Heroes of Might and Magic V, Might & Magic: Heroes VI, and Might & Magic: Heroes VII. It is similar to the grail from Heroes III and Heroes IV, and can be used to construct a grail building. Every faction has its own unique grail building, with different bonuses, but usually includes a large increase to income and creature growth, and some other bonus.
In Heroes V and Heroes VII, the Tear of Asha is found by collecting pieces of the puzzle map from visiting obelisks. The puzzle map will show its location and the player will have to dig for it (in Heroes V) or cast the "Reveal Treasure" adventure map spell (in Heroes VII). There is never more than one Tear of Asha on each map, but sometimes, there's none.
In Heroes VI, it can be found by combining the four Fragments of the Moon Disc, and following the flash that appears on the mini-map. Each skirmish map may have multiple Tears of Asha.