I'm thinking that after you defeat the MVP, you get an aura or a helmet, not both. But the number you get depends on the number of party members you have, that are still in the MVP's room. So, say you defeat the MVP and had 20 ppl in party, but only 8 are still in the MVP chamber, the NPC would only give 8 helmets/auras. That way people can't have giant parties of alts, bring them in and let them die, and use their mains to kill the MVP. They can't farm the equips then. The MVP would also take a LOOOOONG time to kill. Switch elements, use skills, have tons of HP, high def and mdef. Hit extremely hard. So as to try and use every class you can.