http://www.fiestafan.com/wiki/Kingdom_Quests
Kingdom Quest is fairly unique for Fiesta.
It happens once every 2 hrs (frequency differs for different KQ, but most lower level KQs are 2 hrs apart)
You go in as a group of 15 members, and complete the "task" together, and u get a nice chest and exp reward at the end. (As long as you've got a free inventory spot, and that you're not dead as the KQ finishes).
Its a nice change from the normal solo grind. May take a few times to get it right and not die too many times and get to the end. "Becareful and stay alive" would be my advise =D