I'm a Hunter main, but I've encountered a couple of Warlocks using it in PvE during PEs. The first thing I've noticed is that when the Warlock summons the Sword and puts it into the ground, he looks amazing. Second thing, the effect of the Rift is noticeable. Which is really important, 'cos it makes you willing to stay into it. This, for example, didn't happen with the old Titan Ward of Dawn (pre-buff) 'cos the Bubble was useless and you didn't care too much to stay into it. The damage buff is good, the heatlh/shield regeneration too. I think the duration is okay, it would be great if there was an Exotic piece of Equipment to increase the duration of the Mega-Rift. In an organized group against a Boss or crowds of enemies, no dubt you want to have a Warlock with the Mega-Rift with you.