The Earth Sprites. The Elemental Sprites, #2

Long before Marvin first rode Charger, the eastern mountains burned beneath the smoke of the Crown of Embers. Deep inside the volcanic stronghold, Ash Goblin smiths forged a massive hammer for Commander Vark using black iron wrapped around a core of raw ember ore. Eleven earlier attempts had failed, but this weapon survived, its crimson veins glowing with unnatural heat while a strange darkness moved beneath the metal.
Vark believed the Hammer would become the key to breaking ancient protections hidden throughout the world. For years, Vark had collected fragments of stone covered in forgotten symbols describing the Deep Paths, powerful currents of magic running beneath mountains, forests, ruins, and distant lands. The markings spoke of ancient Seals built where those currents gathered and of powerful guardians hidden behind them.
When Vark tested the newly forged Ember Hammer against an enchanted stone slab, three blows shattered what ordinary weapons and fire could not damage. To Vark, the result proved the ancient Seals could also be broken.