In Burning Crusade Classic, many instances are locked if you don't complete certain quests or increase your reputation with certain factions. Moreover, these restrictions also lock out access to later raids in the expansion.
In this guide, we'll explain how to access instances in the Caverns of Time on Heroic difficulty — once you've reached level 70. This includes the Old Hillsbrad Foothills and the Black Morass instances.
Important: All players in the group must have the Key of Time to access any of these instances on Heroic difficulty. If one of the players doesn't have it, he'll be left at the entrance.
To access the Heroic Mode of the instances mentioned above, you must have the Key of Time sold by Alurmi in the Caverns of Time, in Tanaris.
However, in order to obtain this key, you must reach Revered reputation with the Keepers of Time.
To reach such a high level of reputation quickly, we strongly advise you to farm Old Hillsbrad Foothills during your leveling from 66-68 — which should guarantee you Honored — then to continue to farm this instance once you reach the maximum level.