Speak with Eitrigg in Orgrimmar. When you have discussed matters with Eitrigg, seek council from Thrall. You recall having seen Eitrigg in Thrall's chamber.
It had been thought that Rend was slain decades ago.
Seek out the wisdom of Eitrigg, [player]. None know the workings of the Blackrock better than he and if what is written here bares truth, Eitrigg should be informed. No person should be denied the right of vengeance.
You will find him in Orgrimmar.
Once you have spoken with Eitrigg, confer with the Warchief to find out what he wishes to do about this problem.