Human: Write a detailed description of a mysterious scene inside a tunnel cavern with an altar. Assistant: 
A rough chunk of stone rises from the floor as though it grew from the mountains themselves. Closer inspection reveals careful chiseling and subtle carving to create a flat-topped altar. This part of the tunnel is hushed, the stone floor clean, the walls spotless, but thrums with power. Someone -- or something -- keeps the altar in good repair. Small bits of bone and feathers are arranged behind the altar, holding meaning known only to those who laid them there.