• Key of Time
• Binds when picked up
• Unique
• Requires Keepers of Time - Honored
• "Unlocks Heroic Difficulty for Caverns of Time dungeons."
• Sell Price: 2 50
• Vendor 10

Unlocks Heroic Mode key for the Caverns of Time instances:

• Escape from Durnholde Keep
• Opening the Dark Portal

Source

This item is purchased from Alurmi in the Caverns of Time. You must be Honored with the Keepers of Time to buy this item.

Patch changes

Patch 4.2.0 (28-Jun-2011):  
All heroic BC instance keys have been discontinued. All heroic BC instances can now be entered at any reputation level.

Achievements

 The Keymaster

Patch changes

Patch 2.3.0 (13-Nov-2007): Changed amount of reputation required. 

Went from revered to honored.

External links

• Battle.net (EU)
• Wowhead
• Thottbot
• WoWDB