Lineage is having one of the best Halloween events ever right now. We get to run around in costumes and hunt for souls. You collect souls to trade in for some awesome prizes like this one:
A really cute Spartoi Doll! The bonus effect it gives is +3 damage absorption, which is very good, imo. You can combine the effect with items, spells, and food that give damage absorption to reduce your pot usage during hunts.
The various costumes (Black Cat, Death, Vampire, and Witch) are very nice and allows for faster swinging, casting, running, etc. You can also trade in souls for experience candies (150%, 200%, and 250%) but who cares about those.^^ That is all for now!
Good luck and have fun~