Seems as though the event is unable to complete, there is no way to complete Guard the entrance as it requires a "little fire dragon" that never appears. The player starts the fight but instead of lasting multiple fights as advertised by the quest, it last one fight without the monster required to complete the quest.
I've noticed that in the "I want to enchant the energy stone" from npc Mei in the event offers to create a Energy Refresher (Permanent) if you use Energy Refresher x 1, Powerful Stone x2, and Energy Stone x15. I'm hoping this is a glitch as it's seem very foolish to create an item that requires the actual item itself, though the Uber Refresher which requires the exact materials and Energy Refresher (Permanent) is an excellent reward if you can get a hold of a Energy Refresher (Permanent) from a chest as the event cannot currently provide a Energy Refresher (Permanent) for you.
Hope you can fix the glitch(es) on Bosnia Server.