Ever since Sword Art Online: Alicization began, it's been on a time crunch. Kirito's main mission into the Underworld has been to find Alice and remove her Fluctlight from the virtual space before the Final Load Test kicks in and shifts the entire world around. As far as the people of the Underworld know, it's been the lingering threat of the Dark Territory. Although the first half of the third season dealt with Administrator and her troubling rule of the Underworld, the second half has finally unleashed the full force of the monsters in the Dark Territory.
War of Underworld finally lived up to its name with Episode 6 of the series as it officially kicked off the Final Load Test, and the boundary between the Dark Territory and the human world has broken. Which means that a bloody new war between the Integrity Knights and the demons lurking on the other side has begun.
As the Final Load Test begins, the forces of both sides have been gathered in a single canyon. The Integrity Knights are being led by Bercouli and Alice, and the Dark Territory is being led by the Dark Emperor Vecta. It's clear early on that the human side is far outnumbered, and the Dark Territory's forces are far more brutal in their attack patterns.
The orcs and giants begin the first wave of attacks, and the Integrity Knight Deusolbert begins firing his powerful flaming arrow attacks. Although he deals a great amount of damage, he can't quite hold them off forever as he soon runs out of magic power and arrows. This nearly leads to the death of one of his men, but he manages to save them just in time with a last ditch attack. But it's clear that he can't keep this up forever.
It's a much worse affair for Fanatio, who manages to deal a powerful blow to the giant's leader, but when he starts shorting out and has an impact on how her fluctlight works, it freezes her in place. She can't move and is nearly killed, but one of her guarding knights jumps into help her. She loses her life in the process, and the forceful pushback of the giant forces her to bleed from every orifice, but this buys Fanatio the time she needs to defeat the giant.
Although the Dark Territory has taken the first major losses, they still have a huge lineup of warriors ready and waiting to jump into the war. The same can be said for the Integrity Knights, but it's going to get a lot worse before it gets better. Especially with Kirito in the condition he's currently in. If you wanted to jump back into the series, you can currently find Sword Art Online: Alicization - War of Underworld streaming on Crunchyroll, Funimation, HIDIVE, and Hulu.