The World Boss, introduced in Update 28, is a mode where the player fights a powerful boss for WB Coins and its card. It can be accessed with jjk worldboss.
Information
Pressing "Start" uses the attempt, even if the player loses, so be careful! Fights last up to 100 turns, and if time runs out, the team with the higher HP % wins.
Gjallarnhorn, and weekly rotation during its event
400M
The boss changes every week, and the current boss is shown under "Stage Mechanics" in jjk worldboss. Any boss on this list, including The Perfected Being vs. The Perfect Curse, can also be fought at any time by using a Gjallarnhorn.
Continuous Cycle of Balance
The Perfected Being is immune to the last Element that hit it, and Unfavourable Elements deal double damage. Grounded stops this and makes it take 15% more damage (30% from Pirates). King of Curses cards deal 100% more damage in this fight.
World Boss Shop
The shop can be accessed with jjk wb shop, and the prices are in WB Coins. It sells the items of the boss currently in rotation, so each shop below is only open while its boss is the weekly boss.
The next win guarantees the card drop, and the effect stays active if the player loses. It can be bought from Tomura Shigaraki's shop, or from the guild shop at 1 per week.
Father's Hand
Used to evolve Tomura Shigaraki.
Shard of the Ever-Adapting
Used to evolve The Perfected Being.
Gjallarnhorn
Summons a co-op boss for up to 5 players with 1 card each (jjk use gjal <boss> <card>)