(This does not award a quest point.)
Free an imprisoned slave.
The password to ithe Black Gate of Mordor.
Locate the hidden slave, then free him.
The password to Mordor changes each reboot, so once you have gotten the password for the current boot, you do not need to free the slame again.
In order to use the password simply go to the Black Gate (At the gate) and say the password.
say <password>
do move pile,free slave
Leahpar, an orcish slave is tied on the floor will thank you and in return he will provide you with the password to get into Mordor.
Leahpar whispers to you: My savior! In exchange for your kindness, I shall tell you a secret: the password for the Black Gate is '<Mordor password here>'... but I must go now!.
If any of the information here is missing, or wrong, please let us know.