Creating Tier 3 pieces requires a lot of gold, RNG and someone with an
actual Tier 3 achievement! Here's what you need to do in order to craft a
Tier 3 piece:
Loot a Lamented Crusader piece of gear from Zackett's Dented Gear tokens.
Repair
the Lamented piece of gear by using one of the cursed Naxx items
(Cursed Cloth, Languished Leather, Scourged Scales, Undeath Metal).
The recipes can only be obtained by someone who has the achievement
Drop Dead, Gorgeous from collecting a full Tier 3 set, but you can work
order for these if you don't have the achievement. This will turn the
piece into a Desecrated piece of gear.
Once you have a Desecrated piece of gear, you can purify it by using Phylacterweave and Righteous Orb:
Purify Helmet: 280*Phylacterweave, 10*Righteous Orb
Purify Shoulders: 28*Phylacterweave, 10*Righteous Orb
Purify Chestpiece: 210*Phylacterweave, 10*Righteous Orb
Purify Bracers: 70*Phylacterweave, 10*Righteous Orb
Purify Gauntlets: 140*Phylacterweave, 10*Righteous Orb
Purify Belt: 70*Phylacterweave, 10*Righteous Orb
Purify Leggings: 210*Phylacterweave, 10*Righteous Orb
Purify Boots: 140 Phylacterweave, 10*Righteous Orb
A complete set of Tier 3 armor will require 1400*Phylacterweave (or 2.8 million gold in vendor mats), 80*Righteous Orb.
Congratulations, you can now craft Tier 3 gear!