Drag the room and you're level 18 very fast. (Level 20-22 mobs) At level 18 go down to the next floor. From the porter you enter the hall, make a left then follow DFO Gold to the right and it's the first room on your left. (Or simply go left and keep going till you can go left again.) Summon your party on the stairs and drag the entire room until you hit level 24. (Level 20-24 mobs)
If one Tomb is full, move to the next one quickly by porting to a Tomb in another location. When you enter the tomb ignore everything until you get to the bottom of the entry tunnel and the path T's.
This is where you want to farm. (Level 17 mobs) If you are facing the T as you come in then you can pull all of the skeletons to your left, some behind you and up a bit, and many to the right. It's a very big pull area and requires very good armor.
There is a gap in the mobs just to the left of where the T begins and you summon your full party there, against the far wall. You farm here until level 15.
Move to the very bottom of the cave where the porter is to go down into the Tomb. Summon your party into one of the crags past the porter, in the back, and up high away from the mobs.