Some Warehouse Keeper's medals that were being delivered to the Town of Oren were stolen by monsters. Recover them and take them to Warehouse Keeper Cliff of the Town of Oren or Warehouse Keeper Baxt of Hunters Village and you'll be allowed to play bingo.

Monsters to be hunted -
Tanor Canyon: Nightmare Lords, Nightmare Keepers, Nightmare Guides.
Watcher's Tomb: Hunter Gargoyle, Dust Wind
Death Pass: Thunder Worm
Sea of Spores: Rotting Golem, Giant Monster Eye
Outlaw Forest: Hunter Gargoyle
Hunter's Valley: Weird Drake
Swamp of Fire: Tulben, Lord Conjurer, Conjurer
National Cemetery: Grave Guard
Forest of Mirrors: Karinkain