Tal Rasha's Chamber (Diablo II)
Tal Rasha's Chamber is the small chamber found in the True Tomb of Tal Rasha, where Duriel resides. The chamber has no direct access. To enter it, you must insert the Horadric Staff into the orifice in the final room of Tal Rasha's Tomb, which will cause a small passage to open on the wall. Once entered, the chamber cannot be exited the same way however, and must be left by a Town Portal.
After defeating Duriel, the player will find Tyrael trapped in the chamber where Baal was previously imprisoned. He reveals that he came to stop Diablo from freeing Baal, but that he failed. Because of this, he instructs the player to take up the chase in his place and stop the Three. Though it may seem a daunting task for a simple human, Tyrael seems to have been keeping an eye on the hero up until this point, revealing that he "did expect you earlier."
Similar to when Andariel is defeated, Tyrael will open a Town Portal for the player when Duriel has been killed.
Technically speaking the room can be considered to be a level 2 of Tal Rasha's Tomb.