The Locked Lamia Chest  

If you take the 1st left when you enter the caves you come right to him. The exact location of the chest is
-106.53, -4.56, -1129.70. I am lvl43 and I received apporx.- 1/2-1% xp, and 1g 10s 93c. I imagine the xp and the treasure goes up if your lower lvl and they go down for higher lvl.

You must kill Lamia CARVERS until you find 3 keys. Reward is 1g, 7s. Maybe 1-2% xp, not sure at lvl 45. Location of chest is -105, -1128.

The 3 keys to the chest are on Lamias outside of the mine that the chest is in. Get the 3 keys and return to chest to unlock. You will get 1g 8s as reward. I did not notice how much exp if any is rewarded.