Pit of Saron is the second of three World of Warcraft dungeons known collectively as the Frozen Halls. These instances are designed for level 80 characters. Located inside a secured area of Icecrown Citadel on the western side, the Pit is the instance portal on the right of the meeting stone located inside. There are three bosses in Forge of Souls: Forgemaster Garfrost, Ick & Krick, and Scourgelord Tyrannus.
The Pit of Saron as described by Blizzard:
Accessible only to those who have laid waste to the Forge of Souls' unholy operations, the Pit of Saron will bring Horde and Alliance forces deeper into the Lich King's domain. Players who venture here will immediately be confronted by the lord of this lair, Scourgelord Tyrannus. But defeating him will not be as easy as it seems. Before they can present a threat to Tyrannus, the adventurers, instructed by their leaders, will need to free enslaved allies who have been trapped by the Scourge. Until that happens, Tyrannus will leave all adversaries to his minions, workers of the citadel's mines. Perhaps the challenges here will lend clues as to the whereabouts of the Lich King's private chambers outside of the Frozen Throne, deep within the Halls of Reflection.