Yes, Belphegor managed to get Blood Vengence and Pheonix Pyre (and reinvigoration
) off before you paralyzed him. You actually got him down to 10% hp and 100+ fatigue, so one or two more hits would have killed him. But then you routed.
You won the battle of course, as when he became unparalyzed, I hit the turn limit and auto-routed. Running scared of an enemy army that consisted of 2 hibernating bears at 195 fatigue. And he calls himself the lord of hell...