If the statue on the center island is facing the Pillar of Light, this named can spawn on the death of any mob. It spawns a distance away and is not auto-aggro. It's reported to drop any loot that Pillar of Light nameds drop.
His debuff, Light of Erion, appears in the song window and appears to remain up for the entire fight. It's a reverse 800-point damage shield (you lose 800 hitpoints for every one of your melee hits). Also, spell casts cause a self-nuke for 9000. DoTs and pets are most efficient against this mob.