It's ok, though I wonder why it's in the S series. Maybe it will make sense after I read the last 2. Or maybe because it's a module where players have to use more wits? Unsure. To me, modules of this era where all a bit wacko in how much players had to think to get away from certain death.

Noteworthy: the heating-metal room, the water membrane room, the rotating cylinder corridor.

I also like the idea of a lair in a volcano, and how the environment informed the terrain and intricate traps in some of the rooms.