A lot of people would say the Shin Malphur lore, and I would enjoy watching it. But I feel like those types of characters should be left in the lore. Seeing his face, knowing who he is, would hinder his character. The Battle of Six Fronts would probably be the most logical choice, since the backstories of a lot of important characters (Saint, Osiris, Zavala, Ana, Eramis and her council, Cayde and his fireteam, Fikrul, Shaxx, Saladin, etc.) started or converged there.