Key Encounters: The Volcanic Shrine includes 20 tiles—plus one available at the SkeletonKey web site—which you can use on their own or in combination with Volcanic Caves Volume 1 and Volcanic Caves Volume 2 to create interesting and challenging encounter areas inside a live volcano or some other venue where molten lava flows next to solid rock.
The tiles themselves are enough to make this a great product, but Ed Bourelle has gone himself one better. He's teamed up with Monte Cook to provide an actual encounter write-up that uses these particular tiles in a layout that Ed has provided. (Please note, however, that the layout shown on p. 6 of the PDF uses tiles from other SKG products and cannot be fully laid out just with the tiles in Key Encounters: The Volcanic Shrine.) This is not a full adventure, mind you—just a single climactic encounter with a few ideas sprinkled in for splicing the encounter into a larger adventure. The adventure itself assumes a d20/OGL bestiary and a D&D 3.5-style economy, but DMs can easily modify the stats as needed if they choose to use the encounter. Even if they don't, the tiles themselves are quite a treat and a great addition to any DM's box o' props.