Video Summary - Arcane Lineage: Halloween Part 1 Update Quest+ Event Raidboss Guide

Event Quest and Storyline

Start at the Tundra Gate and speak with the NPC fighter. Collect five pumpkins to unlock the event store.
Follow the quest to the theater director, then visit the Beastmaster. In Caldera, the guide recommends entering the house near the quest board to skip the flyer-search step and obtain a horse whistle. The horse can bypass random encounters and help with NPC quests.
The quest reveals that a character’s father was sent to the Shadow Dimension, and you must help retrieve him. Travel through the Shadow Realm, complete several fights in the desert, then return to investigate.
The investigation is a deduction puzzle: examine the dialogue options, connect the relevant clues, and identify the suspect as a merchant from the Shadow Realm.
Confronting the merchant triggers a scripted battle that you’re meant to lose. The merchant has extremely high damage resistance, so losing quickly advances the quest. The scene introduces some of his mechanics and lore about souls and the event’s villain.
After completing the quest, the event store becomes available. It sells candy and other event items; leveling also grants event tokens.

Horse racing is a straightforward way to earn candy. Completing the hoops reportedly awards 16 candies.
Alternatively, spawn the event in the area, defeat mobs, and try to open a portal to the event boss.

The narrator recommends Berserker as the strongest option, with Impaler as another possibility. On Berserker, use lifesteal—the narrator specifically recommends WG gauntlets with lifesteal—to help survive and benefit from Berserker’s damage scaling.
The boss changes its soul color, which changes its mechanics. The narrator finds the black and yellow phases especially favorable for dealing damage, though the exact effects of every color aren’t fully established in the video.
Clear the summoned minions. They act as shields and greatly reduce the damage the boss takes. The boss may also redirect attacks to its horse or other summoned creatures, so deal with those before using your strongest attacks on the boss.
Use single-target attacks to break through armor when the boss or horse is shielded; area attacks are less effective in that situation.
Apply curses only when the boss isn’t immune to curses. The narrator also suggests using Sinister Gaze to remove the boss’s opening damage resistance.
The boss has QTE sequences involving its horse and soul weapons. Failing them causes damage or other penalties, including lost maximum health, though the narrator sometimes chooses to skip them to save time.
Keep some resources in reserve instead of using all your powerful attacks at once. The boss can summon additional minions and interrupt your damage window.