Image: Rebel Wolves / Bandai NamcoOfficial screenshot from Rebel Wolves / Bandai Namco.
Brencis, the vampire Knyaz of Vale Sangora, is the final challenge of the story. You can only face him properly once his three Boyars are dealt with, so plan your court quests around him.
Stay in the middle of the arena and clear wraiths as they come, because they pressure you from the flanks while he holds the centre. Parry his shield-marked swings for counters. Dodge or step out of range on anything with a skull icon. Keep a gap-closer like Charge ready, plus a crowd-clearing ability for each new wave of wraiths.
Finish the court quests for all three Boyars first. Lacra's or Crake's quest lines can give you allies for the fight. Save manually right before the last quest so you can try other endings.
The fight with Brencis creates autosaves as it goes.
Emptying his first bar pulls you into Anachora, where he drops his human form and fights as the Grotesque Ascendant. There are no wraiths, but his long limbs give him much more reach. You start this phase at full health, so spend healing items freely.