Mountain Mist Temple is a location in Falskaar.
600 years before the events detailed in The Heart Chamber, Falskaar was a snowy tundra area and was uninhabitable. There is no known log of what was present on the island at this time, but it can be assumed that there was some habitation here, as Mountain Mist Temple was originally a Nordic burial tomb and likely constructed by the ancient people to honour the Dragons.
When Olav and his party crossed to Falskaar, he spoke to an avatar of Shor: an ancient dragon known as Ahkrinviing. To allow the people to live in peace on the island, Ahkrinviing tore out his heart and gave it to Olav, who used it to immediately terraform the land and make it a habitable land for his people.
Once the land had been terraformed, the people scoured the land for a place to keep the heart safe: the ancient tomb of Mountain Mist Temple was located and the heart stored in an area just beyond the original tomb, a large cavern that was titled The Heart Chamber. Over time, the knowledge of the heart's presence on Falskaar became lost and it was eventually a mere legend, until the events of the main quest.
Related Quests Edit
The Heart of the Gods Edit
The temple can only be accessed during the main quest The Heart of the Gods. During that quest, the Dragonborn is attempting to stop Yngvarr from obtaining the heart and using it for his own ends. Once the quest has been completed, the temple can be revisited, but the Heart Chamber will be sealed and unreachable.