Spiral Abyss can be considered the end game content, that starts at Adventurer Rank 20. You can do this whenever you want once you reach AR 20, and however many times you want since there is no limit.
This content can NOT be played in multiplayer. Inside the Spiral Abyss, you can't consume food to heal, change party members, change artifacts, or level up and ascend characters, so be sure to properly set your team before going in.
There are 8 floors, and each floors have multiple chambers. Clearing floor 8 with 6 stars will permanently unlock the Abyssal Spire. Completing chambers in the abyss will get you rewards that you can view by tapping the "Rewards Preview" at the top.
Clearing a chamber in each floor fast and efficiently will give you stars depending on how well you do. You can get rewards based on how many stars you have on each chamber by tapping on the treasure chest icon.
Spiral Abyss is located in Musk Reef, and you get there by going to Cape Oath. Near the edge of Cape Oath, you will have to find the little ghosts and guide them to their place. After gathering all 3 to their designated area, a wind current will appear for you to fly up. Simply fly to the portal in the air once you are at the top of the wind to be teleported to Musk Reef.
Why you should play Spiral Abyss
Completing each chambers will give Mora, character exp, weapon exp materials, and most importantly, an Artifact box. Additionally, every 3 stars in each floor will get you 100 primogems and some Mora. Completing floor 3 will also reward you with a free Xiangling, a pretty good damage dealer character if you don't have one yet from the gacha.
Floor 1~8 rewards will not get a reset, so they are a one time claim, but floor 9~12 resets every 2 weeks. This is why you want to try and get it done quickly so you can earn those rewards every 2 weeks. Completing each floor from 9 onwards will get you a 5 star artifact box, so this can be a good and reliable way of actually getting a 5 star artifact.
Blessings and Benediction
There's a blessing that is always active whenever you enter the Spiral Abyss. These blessings have varying effects and they change every now and then. Tap the "Blessing of the Abyssal Moon" button at the top to view the current blessing and the remaining time.
In addition to the blessing, there is also "Benedictions". These are effects that you can choose whenever you enter a new chamber. There are a wide range of effects, but the important thing to keep in mind is where is the effect for. At the bottom of each cards, there is a text that says "Effective this floor", or "Effective this chamber". Chamber effects are often more powerful, but they will disappear when you go to the next chamber, while floor buffs will last until you clear that entire floor.
Rewards and Reset
Spiral Abyss is composed of two parts: the "Abyss Corridor" and the "Abyssal Moon Spire." Abyssal Corridor's rewards don't get reset over time. However, Abyssal Moon Spire's reward will get reset every first and sixteenth day of each month.
How to unlock Abyssal Moon Spire?
You can unlock Abyssal Moon Spire by clearing all 8 floors of Abyssal Corridor.