Monster Carnival

This is a competitive Party Quest for characters between levels 30 and 50. You can access to this Party Quest only from Kerning City, Ludibrium and Orbis. Two parties enter a Ludibrium-themed map and compete at killing monsters for CP, or Carnival Points. These CP, in turn, can be used to either slow down the other team, summon monsters on them, or can simply be held. At the end of the time limit, the team with the most CP wins. CP can also be used to summon Monsters on the other team, make the creatures stronger, faster, or make the other players damage decrease.Items dropped in this PQ, will be used once picked up, but etc items will be kept for exchange for weapons and necklaces.

http://strategywiki.org/wiki/MapleStory/Quests/Party_Quests