There should be a cut scene in TTK with Eris, the vanguard and you there about to bury the guardian. After that you are all about to leave and all of a sudden Toland stumbles out of the temple doors all ashy and bruised and aching. He then falls to the ground and you lift him up and take him to the tower. When he arrives he informs you that Oryx has been told of his sons death and his ship now orbits the rings of saturn preparing to attack. The vanguard then start to discuss and try to understand what he is saying and what he has learned while in the hive chambers and why he has not succumb to the darkness. He then slowly gets up to say "I understand the darkness now. And I consumed it." He then shows the va guard his powers that he acquired while in the hive ships and what he had learned. The vanguard nod in agreement and have Eris and Toland guide you through the quest.