The Anti-Scout prevents enemies from compiling information about your Turf. There are are 4-hour, 8-hour, 24-hour, 3-day, and 7-day varieties. The latter 3 can be purchased in the Gem Mall for 600, 1200, and 3000 Gems, respectively.
There have been two special event versions of the Anti-Scout: the Spooky Anti-Scout, and the Warding Lamp. Both prevent Scouting for 5 minutes, and both have been available during Halloween events.