Poinnovation til you can go to crypt of decay, then once you are 65 ish do PoFire til 70-75... a few pulls of the whole/half zone should level you up 5-6 levels a pull....
I just did this strat with 5 new boxes and it took me roughly 3 hours~ playing, most of that was just moving the characters...
looked at the mailbox and on nov 5th at 5:08 i dinged 50 due to the LC quest... from level 1.. now at 6:53 I dinged 65... the same day, I was moving around quite a bit during that time frame too... but 2 hours to go from 50 to 65 I quit that day after that due to having to go to work, then I started on the 6th at 2:57 and dinged 66... then at 3:24 the same day I dinged 70...
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that was my strat for straight power leveling, with my crew of 13 that I had... i could pull 1 whole half of PoFire and not die and have it dead within 2 minutes from ultra mage DS, bard ds and self DS while the lower level bard just aoe'd to get credit