This quest is not available in game.
Take the portal to Undercity located in Grommash Hold and report to Vol'jin.
On the day of my death I wish to be able to say that I lived a life without regret. Those who mourn my passing will know that I was a Warchief who made decisions that best served his people.
But this betrayal by Varimathras and Putress... All that we have worked for is for nothing.
<Thrall's chest heaves with a heavy sigh.>
Justice must be served.
Portals to Undercity will be active momentarily. Vol'jin will be waiting for you. I will meet you there soon. Together we will make it right, <name>.