Borrow high-level units, specifically Butler Faust or Spicebush Yi Sang for Sinking, or Liu Ishmael for Burn.
Dongbaek applies "Blooming" to sinners (stacks up to 5 times). 4:48 subtitles English
If a Sinner is trapped, focus on winning clashes to free them. Borrow high-level units
Reduce Dongbaek’s sanity to negative levels to cause a "Panic" state, which staggers her. 4:48 subtitles English
If you get a "slow" start and lose key clashes in the first 2 turns, resetting the stage is often better than trying to recover.