So this quest thats called "DR. BOOM" is a quest in Netherstorm where you have to bomb this guy that has 640,000HP and the quest uses bombs to kill him whcih do about 30k damage and so you can just sit on the rock as shown in video and use ranged wep to skill up. I sat there for 30 min just lvling up my wands and it was fast! He doesen't attack you back as long as your on the rock where I was at.
(Not sure if you can do this without the quest)
Cords of rock: 34,59
This is very easy skill up on ranged weps for a 67+