This quest begins after you reach the sawmill and speak with Luke and Ronald - which means completing the "Rumors from the Sawmill" quest.
The sawmill rumors proved true. With the Greymanes' reunion successfully concluded, return to Howling Hill to prepare the next phase of the plan.
Rewards: 200 Camp Oats, 200 Camp Coins, Thick Hide x6, Iron Ore x5
Return to the camp by any means - the fastest way is to use the Abyss Nexus. As soon as you approach the camp, you will receive the next objective for this quest.
Approach the small shrine that has appeared in the camp.
Approach the shrine and examine the Dragon Head Statue. You will find a letter inside.
You should find Shakatu's Letter in your inventory. To finish this quest, read through its contents.
Additional instructions will appear on the screen regarding how to complete camp missions - which are the objective of the next quest - "Bustling Hill."
Unknown crates and bundles were waiting at the camp. It seems Shakatu kept his promise to support the Greymanes' cause.