Tolland the Shattered was a voidwalker warlock who had a huge interest in understanding the hive. Because of his curiosity he was exiled from the city and labeled as a mad man. Later Eris asked him to join her on their journey into the hellmouth with the intent of killing Crota and re-capturing the moon. How he died or whether he died is still unknown. But If he is alive he is still down in the hellmouth somewhere because while he and Eris were escaping he went back in after they heard a scream from one of their lost fireteam member. He also made the guns Shadow price and Bad Juju as you stated.