Overall, the build is nice for the lower Torment levels. Having used full Invokers, Demon 6k bonus, Sang bracers, % physical with soj, andys, bracers, and doombringer and achieved 85 mill on reflective skin last week, its just not viable on higher torment levels. It takes away from too many other useful slots in a build. The damage is nothing more than spike damage, and unless you can keep Akarats up forever or have a ton of CDR, its just there to assist with Frozen, electrified, orbiter, and thunderstorm, and reflect damage mobs. I use it as a supplementary skill now, along side with my Foot+Board combo. Would also go good as a side skill with a hammer build.
To add, The invokers set is garbage except for the 4000 thorns increase. The 15 yard thorns does not apply to iron skin.
Best thing to do is to stack STR, secondary thorns affixes, two piece invokers, two piece demons, and use iron skin as a CC breaker or heavy hitter with the proper elite affixes. Focusing your gear for lightning/holy will pay off more in the long run. Death Watch mantle is another good shoulder to combine with provoke, using it a long time ago it would proc 3 million fan of knives hits, which isnt a bad affix at all.
When blizzard does decide to give thorns (passive) an overhaul, ill put the thorns gear back on. Until then, FotF, Shaefers, Prophecy, and Foot Combo are the higher torment heavy hitters. You can add me if you'd like, i'm always down to do t3-t6 rifts and I dont bum :)