The Harvest Behind Stone - AI-generated fantasy Puzzle

The Harvest Behind Stone

You find a circular cavern whose walls sweat cold water and echo with a slow, irregular dripping. A massive stone slab seals the far side, its surface carved with a faded red spiral and three kneeling figures. Before it stand three waist-high pedestals: one bears a bronze bowl of warm red blood, one a silver bowl containing five tarnished coins, and one a tied linen bag of dry grains. At the center of the slab is a fist-sized hole ringed by narrow metal grooves. Old scratches and rust stains around the hole suggest that the wall has punished previous attempts.