Glitching Elder Panini is apparently possible. The boss where you get the second shard of Epoch. I only did this once so I am not entirely sure what triggered it.
Situation:
Level 12 Sentinel, using Lunge and Vengeance. Boss Health was between 50 and 75%. He did the teleport move to the edge of the room. Wherein I hit him with Lunge, and then just held down Vengeance attack until he died. His voice lines continued to trigger as his health went down but he himself did nothing.