I would like to know that too. What I've figured out so far: Drahque's LoN Blessed Shield build is heavily group-focused, it lacks survivability for solo. With a few adjustments, one will be able to us it in solo-games, but I don't know how succesful that would be.
Yesterday I put together a suboptimal LoN Blessed Shield to try in a group with a Wiz friend. Had 5 ancient items total with random stats, sometimes quite useless, and didn't have Pain Enhancer at all. We were able to clear GR60 in 8 minutes, which was slow compared to our usual runs, but build was fun and the overall impression was that it should be quite viable in groups. Still that's just my impression. In the end I'd also like to know if someone mains that build and could elaborate on its potential.
I find that the his is a very viable build. I cleared GR73, will work on 74 tonight. For solo, you must have Unity cubed and for group play, you use CoE. I have no issues with group play as I have played in 70+ rifts with this build and I was the main tank. Only half my gear is augmented, once it is all augmented, I will be able to go higher.
I find it's not that viable for higher GRs. You lose too much mitigation compared to other builds. The nice thing about LoN bombard is that you can gear around having much higher toughness than shield, since you need dps stats for shield to be effective. I enjoyed shield for half a week or so farming TX and some GRs, but after swapping to LoN bombard last night, I can't go back to shield. It's too underpowered in comparison.