Recap / Sword Art Online Calibur Arc

Some time after the murder cases revolving Gun Gale Online are resolved, Kirito and Leafa discover the legendary sword, "Excalibur", in Alfheim Online. While they couldn't reach it at the time, with the sword being held in a very difficult labyrinth, other players have begun to see it. It would only be a matter of time before everyone started coming for the sword, so Kirito and Leafa decide to gather their friends and lay claim to it first.

In ALO, they learn from Yui that an event was ongoing, with players attacking monsters in the hopes of obtaining Excalibur. They make their way to the labyrinth, where they are greeted by the "Lady of the Lake" Uror, an NPC with sophistication not dissimilar to an artificial intelligence like Yui. From Uror, they learn that Thyrm, a titanic monster, had tricked other players into carrying out wholesale slaughter on innocent monsters in preparation for a large-scale invasion. The stakes are far greater than the average player realizes: the Cardinal system that ALO was built from had the power to radically alter the game under certain conditions, as it had when it destroyed Aincrad in Sword Art Online. If Thyrm's plan succeeded, ALO would never be the same. The only way to prevent a potential cataclysm is to retrieve Excalibur from the labyrinth in the bottom of the frozen lake of Joturnheimr first.

The battles in the labyrinth are tougher than any Kirito and his friends had fought before. A pair of bosses that are respectively resistant against weapons and magic give the group trouble, until Kirito implements a new skill he had been working on: "Skill Connect". Unlike SAO, ALO did not have a proper "Dual Wielding" skill for Kirito to use. Instead, Kirito would equip one-handed swords in each hand, then initiate Sword Skills alternately with each sword, bypassing the cooldown limitations of both weapons and attacking rapidly, felling the bosses.

Deeper into the labyrinth, the party find and rescue a trapped NPC named Freyja. Upon joining the party, Freyja gives the party a massive buff as they make their way to the dungeon's final boss, Thyrm. As the battle intensifies, Kirito retrieves a golden hammer and tosses it to Freyja, who transforms into the thunder god Thor and destroys Thyrm, opening the way to Excalibur's chamber.

Upon pulling Excalibur from its plinth, the labyrinth begins to collapse. A friendly monster saves Kirito's party, but it seems as though Excalibur would plummet into the depths below and be lost forever. Thankfully, however, Sinon manages to save it, using a combination of magic and impeccable aiming skills developed in Gun Gale Online to fire a tethered arrow at Excalibur and retrieving it for Kirito.

With the frozen wasteland beneath the labyrinth transformed into a verdant paradise, Kirito completes the quest and earns Excalibur as a reward.