Human: Produce a detailed written description of a eerie scene outside a cavern with a slab. Assistant: 
A broad round slab of polished marble dominates this tiny niche, covered in strange runic inscriptions. The walls are made of chiseled granite blocks, clashing with the natural limestone of the cavern outside. The floor around the slab is scratched and gouged, as if some burrowing animal has been digging at it.