[Original post authored by Froszen - topic moved from old forum]
his quest actually is not hidden, but almost no one is patient enough to get it. After hundreds of time talking with Duke of Deer, the quest symbol above his head will disappear, you will receive a quest that tells you to go talking to a NPC and get 3K exp). After finish this quest, the quest symbol above Duke of Deer will appear again then you can talk with him hudreds of time before get your new 3K exp =)). Sometimes he will tell you: "Yeah, i like young boy having an inquiring mind" and give you 10K Gold. ^^;
Someone will confirm level of this quest. I found it yesterday. I'm 9x now but i'm sure this quest can be receieved at level 8x (about 86+). You don't have any information about this quest; won't receieve from any NPC. Just go to right location and get it automatically.
Here its cordinate (214, 862). Go around this cordinate and you'll be received it. The story is: " Dragon-bone Riders (lv 87) had a plan to invade grassland. A family of citizens found out their scheme and write a letter to a NPC at Universal City to inform him about that. But they were killed on their way to Universal City. You discovered their corpse and the letter. Now, time for revenge!" Very Happy