Hammer that Tempers Gold within the Earth

Hammer that Tempers Gold within the Earth (地の中で黄金を鍛える槌) was a Norse Magic Cabal, one of five who united to attack Brunhild Eiktobel's cabal and were subsequently destroyed by her in revenge.

Background
Five years ago, the Hammer that Tempers Gold within the Earth, together with Those Who Prevent the Extermination of the World Tree, the Iron Stake that Carves Knowledge, Champions from the Sea and Those who Know the Rune of the God’s Sword, attacked Brunhild Eiktobel's cabal out of fear that her nature as a Saint and Valkyrie would cause pure Norse-style magic to go into decline.

Toaru Majutsu no Index SS: Kanzaki
The cabal was the last to be crushed when Brunhild initiated her revenge against the five cabals.