Digging demands the whole amount of a hero's movement points so it is not possible to dig at the same day when a hero crossed even just one tile on the map.

A hero without empty slots in a backpack cannot dig. In order to recover the Grail, a hero must dig it out of the ground. Additionally, every town has its own unique bonuses. The growth bonus applies after all the modifiers: external dwellings and Statue of Legion or its components. The primary bonuses of Grail Building for all towns are extra 5000 generation per day and 50% additional creature growth per week (rounded down). Recovering the Grail artifact and taking it to any town enables the player to build town specific Grail Building. The Grail is typically hidden somewhere in the ground of adventure map, and finding it requires digging it with a hero. In fact, the Grail is sometimes unofficially referred to as the ultimate artifact.

Also it can be sold for 1 unit of any resource. The Grail is an item similar to an artifact in the sense that heroes can carry it and exchange it between them in the same way as artifacts.

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