PS: Make sure to read the updates below for any additional notes such as edits and things such as alternative gear suggestions.
Helm - http://us.battle.net/d3/en/item/crown-of-the-invoker
Shoulders - http://us.battle.net/d3/en/item/burden-of-the-invoker
Gloves - http://us.battle.net/d3/en/item/pride-of-the-invoker
Chest - http://us.battle.net/d3/en/artisan/blacksmith/recipe/demons-marrow
Wrist - http://us.battle.net/d3/en/item/sanguinary-vambraces-1385JU
Belt - http://us.battle.net/d3/en/artisan/blacksmith/recipe/demons-restraint
Pants - http://us.battle.net/d3/en/artisan/blacksmith/recipe/captain-crimsons-thrust
Boots - http://us.battle.net/d3/en/artisan/blacksmith/recipe/captain-crimsons-waders
Ring - http://us.battle.net/d3/en/item/ring-of-royal-grandeur-3qRFop
Ring 2 - http://us.battle.net/d3/en/item/justice-lantern
Ammy - http://us.battle.net/d3/en/item/the-flavor-of-time
Weapon - Current WIP
Shield - http://us.battle.net/d3/en/item/akarats-awakening
Gear Choice Explination
A number of things I have going here;
Ring of Royal Grandeur - Using 3 sets here and getting very important set bonuses for all of them.
Justice Lantern - Block Chance is huge with Akarat's Awakening, and the more block chance you have means the lower your cooldowns will be.
Flavor of Time - The cooldown reduction is the main stat here and the movement speed is also great (meaning that you hit your cap sooner and don't have to get it elsewhere); Amulets are really the most free item with this build but the main thing is you want to get as many of your high priority stats (which I'll cover below) as possible.
Sanguinary Vambraces - No explanation needed
Invoker Set - Key for a thorns build, most pieces roll thorns damage and the set bonus grants additional thorns as well as turning thorns into an aoe effect (due to the ring you only need 3 pieces to get the 4 set bonus)
Demon Set - Mostly here for a nice chunk of bonus thorns damage (there really aren't many better choices for a chest piece; so snagging this set bonus doesn't really hurt you at all)
Captain Crimson's Set - This may seem a bit off, but one huge factor to this build being viable is the highest possible upkeep, and the cooldown reduction from the 3 set really helps with this.
Weapon currently in progress, doing research to find the most efficient weapon for the build since the previous weapon choice doesn't work (although with that being said I don't suggest taking Hack since it does nothing for the build and is more for a build with thorns as opposed to the thorns build I'm trying to achieve).
Akarat's Awakening might seem like another odd choice, given the alternatives (increasing thorn damage by 200% during the duration of provoke namely); however this goes back to how key maximizing the uptime of Iron Skin and Provoke is; while the 200% damage would be nice, having a higher upkeep on your two core abilities is much more important. It's also worth noting that thorns by themselves cannot crit; however they can crit with Iron Skin (which is why it's so important).
Skill choices -
Punish - Roar; The choice was roar or Retaliate for "pseudo-thorns" and Roar all-in-all seems more effective while still being thematic.
Please see second post for details (this is more of a utility slot than anything since your primary damage source is thorns).
Iron Skin - Reflective Skin; This is the only reason this build really works at all, since this is an ability, it allows your thorns to crit (which is modified by your crit damage). Having a high cooldown reduction and keeping this up as much as possible will maximize your damage output.
Provoke - Hit Me; Taunts targets to attack you giving more thorn procs potentially (and give a higher block chance which yields CDR with your shield). Possible change soon since Taunt seems to have a clunky interaction with monsters.
Laws of Valor - Critical; Not really much to say about this except it gives a nice chunk of damage to your thorns when you have Iron Skin up, cdr and your shield will make even more use of this ability.
Akarat's Champion - Rally; This is basically free bonus damage in nearly every way imaginable, and it gives you even more cooldown reduction for it's duration which allows for easier upkeep of your key skills.
Iron Maiden; Duh?
Hold Your Ground; You want as much block chance as possible, and losing dodge for this is a no brainer
Renewal; A nice chunk of passive regen since you'll be blocking a lot
Divine Fortress; Huge survability boost with your items.