The No. 11 Ravens (23-9) snapped a 44-year tournament drought and won its first regular season HAAC title in head coach Ryan Moody's third year on the job.
Vanguard wouldn't allow BC to extend it season beyond the second round of the tournament.
The Lions efficiently scored 16 points off 12 Raven turnovers, and four Vanguard players scored in double figures led by DeAngelo Jones 25 points -- 15 coming from the free throw line.
Senior Charlie Wallrapp completed his final game at Benedictine with 21 points and 11 rebounds. It's Wallrapp's sixth double-double of the season.
John Harris, Jr. also scored 21 points in the loss.
Vanguard advances to face No. 14 Georgetown in Saturday's quarterfinals.