You can find the Halls of Reflection dungeon within Icecrown.
The coordinates are (52.2,89.1)
When start you will fight waves of mobs and the first 2 bosses in Sword’s Rest. Then the end room with final boss you will be running and fighting, follow Sylvanas instructions.
/i Strikes a player for physical damage. Avoid standing in Well of Corruption, the purple circles. Corrupted Flesh reduces max health for 8 sec. Deals ticking shadow damage to a player.
3. Escape from Arthas