Event Period: From October 20 until November 3 Kill monsters and you might be able to harvest their souls! If you are successful in doing so, you will find an "Harvested Monster Soul". If you trade these to any of the Necromancer Guild NPCs, who can be found in Horizon, Katan, Laksy, Rondo or City of Ruins, you will be able to get powerful buffs or mysterious artifacts. Give 1 Harvested Monster Souls to any of the NPCs to randomly get one of the following rewards:
Pumpkin Candy
Halloween Candy
Halloween Cookie
Halloween Pumpkin
Halloween Candy Pack
Halloween Cookie Pack
Spooky Stamina Saver
Cursed Animal Cracker
Unholy Potion
Frankenstein's Bottle
Ultimate Witch Boss Card
Halloween Monkey Hat (365 Days)
Halloween Gentleman Top Hat (365 Days)