Heroic Mode Keys

Auchenai Key
(Everyone in the party needs this key to be able to play this heroic instance)
Requires Lower City - Revered
"Unlocks access to Heroic mode for Auchindoun dungeons."
Sells in: Shattrath City, Lower City
Npc: Nakodu

Flamewrought Key
(Everyone in the party needs this key to be able to play this heroic instance)
Requires Honor Hold or Thrallmar - Revered
"Unlocks Heroic Difficulty for Hellfire Citadel dungeons."
Sells in: Hellfire Peninsula, Honor Hold (Alliance), Thrallmar (Horde)
Npc: Logistics Officer Ulrike

Key of Time
(Everyone in the party needs this key to be able to play this heroic instance)
Requires Keepers of Time - Revered
"Unlocks Heroic Difficulty for Caverns of Time dungeons."
Sells in: Tanaris, Caverns of Time
Npc: Alurmi

Reservoir Key
(Everyone in the party needs this key to be able to play this heroic instance)
Requires Cenarion Expedition - Revered
"Unlocks Heroic Difficulty for Coilfang Reservoir dungeons."
Sells in: Zangarmarsh, Cenarion Refuge
Npc: Fedryen Swiftspear

Warpforged Key
(Everyone in the party needs this key to be able to play this heroic instance)
Requires The Sha'tar - Revered
"Unlocks Heroic Difficulty for Tempest Keep dungeons."
Sells in: Shattrath City, Terrace of Light
Npc: Almaador