This method involves running through level 1 without attacking monsters, then using a staff of charged bolt to clear many monsters at once.
This saves a lot of time as you will clear out monsters standing in your way, and will not have to stop to individually attack each one. The cost to recharge the staves is very low, and the price per charge decreases as the max charges of the staff goes up. With a 78 charge staff it cost me about 5.5 gold per charge. With a 237 charge staff (bountiful staff of charged bolt) it costs 1.75 per charge.
This method involves a lot of preparation, and has not yet been fully tested. The idea behind shadow farming is to get gear with "of the Night" suffix and use a low light radius to run through the dungeons almost undetected.
This avoids collecting large groups of monsters following you around and make it a great deal easier to explore the dungeon without wasting time on killing things that are in your way.