Experience Cave

The Experience Cave can be found North of Nomad-Nur at the X:

The inside of the cave is pretty small, which sometimes can be a good thing since you can run in and out very fast to re-spawn the cave as you defeat all the enemies in it:

What makes this cave interesting however is the statue at the rear of the cave:

The cave is filled with the Undead and with the help of the statue you can get a good amount of experience at a fast pace: