Location: (214 862) or so
Req: Lv. 89 or so? I was Lv. 89 when I got it so I don't know the minimum Lv. req.
Goals: -Step 1. Kill 90 Ossaur Cavalries.
-Step 2. Take the Mysterious Letter Quest Item to Lei Wanchun.
How to get: Go over to the location, you'll see some wagons and some dead people around. You'll get a random pop-up that says something about they killed everyone, even the women and children and you'll get the quest received.
Reward: 33300 coins, 55500 xp, 12600 sp, 9 rep, 1 celestone fragment
This quest is not received from any NPC, is not listed in the find quest section, and is not listed in any PW quest resource site. Found first by yours truly. :D