I’ve been working on this since 2 days ago but unfortunately Youtube is taking forever to upload an 11GB video. In any case, this is my own attempt to clear Abyss 12 and I added text commentary as subtitles in the video to help other players out.
Video available here:
These tips are for the specific comp I brought, but it may work with you, too. I plan on playing through Floor 12 again and refining my strategy but consult with other resources on the next attempt to further optimize.
First Half: Keqing / Xingqiu / Xiangling / Bennett
Xingqiu can be replaced by Beidou: important thing is the additional DR as well as shield her C1 provides
We bring overload for stagger vs Geovishap in Chamber 1, and the flexibility to deal with cryo cicin mage in Chamber 2. Chamber 3 is about toughing it out with Xingqiu/Beidou DR/Shields + Bennett Healing, and doing as much damage as possible within the time limit.
Second Half: Ganyu / Tartaglia / Venti / Diona
Ganyu can be replaced with Kaeya.
Tartaglia can be replaced with Barbara, or Xingqiu.
Venti can be replaced with Sucrose.
Freeze deals with Geovishaps and Ruin Graders in Floors 1 and 3 respectively, while Venti/Sucrose deals with Chamber 2’s Agent and Treasure Hoarder, for crowd control and grouping.
Also, here’s an excellent Guide by Syleza, we may differ from strategy used since I didn’t consult his guide on F12 beforehand. Also a useful companion doc for your Abyss needs, not just floor 12.