You’ll have to be level 65 or higher to participate. In short, it looks like the Valkyon Federation is calling on us to fight back against the monster population. For your heroic efforts, you’ll be compensated with Hunter’s Tokens.
You can kill monsters each week, and the more monsters you kill, the more tokens you earn. Additionally, some dungeon bosses will also drop these tokens. You can use these tokens along with a token convertor to create a Special Mission Missive. You can trade in these missives to buy Exodor Superior Boxes, Skill Advancement Tomes, EP II, and A Big Bear Bag Ticket.
You can also exchange tokens for Sapphires, Dark Shard Feedstock, Eternal Gear Tokens, Skill Advancement Boxes, and event consumables. You can check out the full list of dungeons which drop tokens, along with a dungeon token shop listing loads of items and their prices, on the official forum post here.