Demon Hunter Pain Bringer Invulnerability

It is still currently possible as of today to keep stacking painbringer (Each soul fragment you consume reduces all damage you take by 3% for 4 seconds) indefinitely. The painbringer buff refreshes every time a soul fragment is consumed during the 4 second window, so as long as you can generate and use a soul fragment every 4 seconds it will never drop.

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