It's small instance event (solo)
Kill a few mobs to get to a boss, kill it and claim a reward. Pretty simple, just check it out if u want
NPC in giran center to enter instance and exchange event coins you can get inside for some hats (adjust mob stats, rewards, npc skills etc to your liking...
Credits: l2j-forum
http://www.4shared.com/file/258144163/fe33b6ac/Instance_Event.html