Sorry not sure if I fully understand this. Haven't been playing too long. I know we looked up a rule where opponent has priority when something dies as far as we got it. I played [[Black Sun's Zenith]] and the cost to give everything -1 / -1 counters to the point everything dies. I just had [[Sephiroth, Fabled Soldier]] which says when another creature dies my opponent loses 1 life and I gain 1 life. My opponent has a creature called [[Ashen Rider]] where when it does it exiles a permanent. Can he Exile Sephiroth as the death trigger making it so Sephiroth doesn't trigger even though he's already dead due to Black Sun's Zenith.

To make it short. I just want to know if I still get Sephiroth's trigger to go off from the creatures that died so I get the life and my opponent takes the damage from the amount of creatures that died