File:Bibe's Accompanist (Ripostes).gif

Summary
You can actually activate a riposte on the flames being fired from the cannon ports, as well, but it's just not that reliable, on top of the fact that each Accompanist has pretty simple parry / riposte openings. It's a very fun fight, and getting to see the Acolyte serenade the dance you do with his minions is probably one of the most unique takes on a boss fight I've seen in years.