Rogue Galaxy Quarry: The Desert Idol
The closest save point to teleport to in order to reach The Desert Idol is Kuje Desert - Near the Monument. Once you arrive you'll want to head north once you arrive. The ? Circle you're after is in the center of the desert, if you teleport to really any of the locations and head into the center you'll find the guy.
The item required to summon The Desert Idol is an Alluring Lamp.
If you are missing the item required to summon this boss grind some battles and cross your fingers or go treasure chest hunting on a planet you've 100% the map on. In Rogue Galaxy once you pass a certain chapter the loot table of items that can drop for you ingame is updated.
What I mean is, every item has a chance of dropping off every creature after you've passed that chapter that allows that item to drop. At least this is how it works in my experience. Therefore, if you're missing any items to summon any of the quarry bosses all you need to do is grind a little until you get that item to drop for you. Good luck!