You can fairly easily find the passage with these guys. There are two ways to enter, but only one to get out. The first way is down the hidden ramp. You go into some rooms with goblins nearby the ruby mining room (looks like lava partially hardened on the walls), but if you go in there, you've gone too far. The second room, I do believe it is, has a door leading to a couple goblins near a fireplace. Go to the right of the door and run straight into the wall. The blazing elementals and the reckless efreeti will be waiting for you.
The second way is the path I took. You go into the room with the rubies and somewhere in the western area of the room there's a false floor, lev yourself down (or just fall, it's not that far), and you'll get the blazing eles on you pretty fast. Don't worry, your pet's not far behind.
Pretty boring camp, got my Power of Fire in a few hours. Rohane's guide, found here, says it's generally a 3-5 hour camp.