Beneath Red Mountain, Dwemer miners discovered a great magical stone. By diverse methods, Lord Kagrenac, High Priest and Magecrafter of the ancient Dwemer, determined that this magical stone was the heart of the god Lorkhan, cast here in the Dawn Era as punishment for his mischief in creating the mortal world. Determined to use its divine powers to create a new god for the exclusive benefit of the Dwemer, Kagrenac forged three great enchanted artifacts, which are called Kagrenac's Tools. Wraithguard is an enchanted gauntlet to protect its wearer from destruction when tapping the heart's power. Sunder is an enchanted hammer to strike the heart and produce the exact volume and quality of power desired. Keening is an enchanted blade that is used to flay and focus the power that rises from the heart.
One account stated that the hammer Sunder was wielded by Dumac Dwarfking during his battle with Wulfharth in the Red Mountain. Where Alandro Sul was using Wraithguard in a chest-plate form and was blinded by Wulfharth with a shout, Dumac used Sunder to make Wulfharth's Heart of Lorkhan solid before being slain by him. Indoril Nerevar used Keening in a surprise attack to kill Wulfhearth and cut out his heart. Following Wulfharth's defeat, all three artifacts came into the possession of the Almsivi following the Battle of Red Mountain. The Tribunal wrested Kagrenac's Tools and the Heart of Lorkhan from Voryn Dagoth and used them to give themselves divine powers. Unbeknownst to them, Voryn Dagoth did not die from their conflict but had secretly connected himself to the Heart long ago, turning into Dagoth Ur and becoming a divine being himself.
Around 2E 582 Sunder was known to be broken, as the haft was separated from the rest of the artifact, though it was later reforged. Sunder, along with Keening, was subsequently lost during an annual pilgrimage to the Heart some time in the Third Era.
- In Online, the haft of Sunder can be found, implying it was broken before being found reforged in Morrowind.
- In Skyrim, during the quest "Arniel's Endeavor," Arniel Gane mentions Sunder.
- The description "of divine mass" may be a reference to Mjölnir, the hammer of Thor. Mjölnir is said to be so heavy that even the mighty Thor required his Járngreipr, iron gauntlets which increased his strength, to wield.
- Sunder's appearance is that of a straight-peen hammer.
- There is a voice over for Dagoth Ur that goes unused, referencing a "false copy" of Sunder. No such item is available in the game. However, two unused copies of said hammer, both labeled **Sunder**, can be found in the Construction Set. Additionally, in Plan to Defeat Dagoth Ur, Vivec mentions, "If Nerevarine can equip [Sunder or Keening] while not wearing Wraithguard and receive no injury, the item is a counterfeit." A counterfeit version of Sunder was most likely planned for the game but later scrapped.
- Sunder also appears as an unobtainable card during the "The Tools", a quest in Legends story expansion Return to Clockwork City.
- The Elder Scrolls III: Morrowind
- The Elder Scrolls V: Skyrim (mentioned only)
- The Elder Scrolls Online