Arystidis
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The lamps are not found in units; they simply lie peacefully in the deserts.
They are located in:
Evenmore Island, on the other side of the island with the tavern
Deya in the desert
and also, I think, in Brakada
What do you mean by "zombie"? Do you have a pirated copy? There is no such state in the game.
Regarding artifacts, they only appear when the number of artifacts with heroes is less than 10, and after that, the chances of them appearing become smaller and smaller.