This quest will be available only AFTER you've visited Thurgadin, AFTER reaching level 90 tradeskill.
NOT GETTING THE QUEST FROM QHO? If you have the mail from Qho and when you visit him, you do not see a purple quest marker above his head, delete the mail from Qho and zone into Thurgadin. You will receive another copy of the mail. When you return to Mara, the quest should be active.
To speed things up, before you leave Mara, go into the bar across from the South Sea tents and buy a Return to Mara (one use) stone for 6g from Koros Splinterlimb, the South Sea merchant who is drinking at the bar. Use it after you finish gathering the harvests to teleport back to Mara quickly. These can be purchased in stacks of 20.
If you lose Qho during any of these steps, you can go back to Lian Augren and tell her you can't find him.
If you've already been there you can take the griffin; otherwise, head for the city exit labeled "The Great Divide- Dain's Last Stand" at ( 673, -246, 56 ) /waypoint 673, -246, 56 and head southeast to ( 351, -15, 533 ) /waypoint 351, -15, 533.