King William Street

Take these quests - Demons of Notoriety + Daddy's dead Accept the quests as you normally would, go in the portal and clean out the instance (kill bosses)use the 1 way teleport back to town
sell everything abandon the quests
accept the quests again go back in (after your first time its going to be twice as easy because the other monsters are already dead)

Those two bosses are really easy to get to and it's the only exploit I know of that isn't patched. As I said before I figured this out by myself so feel free to share it with others.

This may just apply to me but after the first kill the bosses are always on together on the first left turn, I hope it's like this for you guys too!

I have also tested the to-and-back teleport and it works that way too, this can save you some time if the bosses spawned too far.