The armor rating of this armor ranges between based on the metal used. This heavy armor schematic is rewarded from a mission on the War Room at Skyhold, after completing the quest at Adamant Fortress, and after judging the Warden Ser Ruth at Skyhold with forgiveness, then a War Room mission titled 'Judgement: The Good Works of Ser Ruth' will be available now, complete the mission at the War Room and you'll be awarded 3 armor schematics including this schematic.
The best crafting recipe for this armor is: 23 Dragon Bone (or Ice Dragon Bone) + 12 Craggy Skin (or Lurker Scales) + 8 Imperial Vestment Cotton + 8 Hardened Gurn Hide.
This heavy armor schematic is obtained from the Trespasser DLC.