Thorn-veined Understone

Thorn-veined Understone is a fist-sized shard of dense green-black stone, warm to the touch even in freezing dungeon air. Its surface bears a natural spiral pattern like a thorned vine curling inward toward a dark, glassy core. When struck against metal, it produces a deep ringing note and briefly reveals hair-thin crimson lines beneath the stone. The shard is too small and irregular to serve as a weapon by itself, but a skilled armorer or enchanter can grind, set, or fuse it into a larger piece of equipment.