The Spaulder of Ruin is one of three Mythics introduced with Update 32 - otherwise known as the Deadlands DLC. At the time of the release, it's considered to be a "best-in-slot" Mythic piece for supports due to the bonus it offers to groups.
Like all other Mythic items, the Spaulder of Ruin can be found by finding a total of five different and unique Leads. Upon finding Leads, one must Scry for the Leads' locations and then Excavate them through the Antiquities Skill Lines under the World Skills ingame.
You can obtain the Aureal Armor Glaze by killing the World Boss near the Shivering Shrine and looting it from their corpse in the zone of Stonefalls.
You can obtain the Petrified Daedroth Horn lead by killing and looting the Abomination World Boss (Mehrunic Mantikora - the name is Taupezu Azzida) in the zone of Deadlands.
You can kill and loot off of any Dremora in any place - instanced dungeons, delves or overland zones - to procure the Void Alloy Rivets lead.
You can kill and loot off of any Clannfear in any place - instanced dungeons, delves or overland zones - to procure the Clannfear Leather Strapping lead.
A very convenient place to get this Lead and the Void Alloy Rivets lead are locations such as the Cave of Trophies delve in the Coldharbour zone where both Dremora and Clannfear adds can spawn.
You can find the Void Alloy Lame Plates by lockpicking and then looting the Safeboxes (silver chests) scattered around the town of Leyawiin in various locations such as private houses or near merchants.