#1 - Aug. 21, 2016, 11:45 p.m.
This can be achieved fairly reliably using a combination of fracture, soul carver, fallout, and as much haste as possible. Simply spam fracture in place of soul cleave and be sure to stagger picking up orbs that spawn to keep the buff refreshed.
Screenshot of the buff stacked past 100% (37 stacks, 111% dmg taken reduced): http://imgur.com/a/z20Uq