You can beat prologue Brencis, but his true form is effectively unbeatable

GG Brief Editorial Desk · AI-assisted, source attributed

Players can defeat the prologue boss Brencis by using Perfect Blocks and dodges, but doing so triggers a cutscene where he transforms into Brencis, Grotesque Ascendant and immediately becomes a second boss. The Grotesque Ascendant deals one-hit kills, takes negligible damage even with top early-game gear, and grows harder across two additional health phases. There is no quicksave before that second fight, so every attempt requires defeating the regular Brencis first; dying to the initial Brencis plays a cutscene and progresses the story as intended.