Here's the list of the level 50 dungeons from here
The Wanderer's Palace
Amdapor Keep
Pharos Sirius
Copperbell Mines (Hard)
Haukke Manor (Hard)
The Lost City of Amdapor
Halatali (Hard)
Brayflox's Longstop (Hard)
Hullbreaker Isle
The Stone Vigil (Hard)
Tam-Tara Deepcroft (Hard)
Snowcloak
Sastasha (Hard)
The Sunken Temple of Qarn (Hard)
The Keeper of the Lake
The Wanderer's Palace (Hard)
Amdapor Keep (Hard)