Curse tablets are not uncommon in the ancient world. They are usually not on stone, however -- they were written or painted on shards of pottery, and later were inscribed on small, thin plates of lead. The intention was to cause someone fear, dread and distress until that person rectified whatever offense he had committed against the person casting the curse. They were really a kind of appeal to the sense of justice of the gods. "Make so-and-so's life miserable until he gives back what he stole from me; or makes restitution for his wrong." They were not so much, "I'm going to curse you so that you suffer and die because I hate you." Making curse tablets was a kind of institution in some places. There were actually scribes who made their living by inscribing lead curse tablets for average people with a grievance. I suppose in those times there wasn't much recourse under the law, so people went to the gods with their grievances.