Item from Solo Leveling by Chugong
The crystallized power of Shadow Monarch Ashborn — absorbing it transforms Jinwoo from a vessel into the true Shadow Monarch.
The Black Heart is the culmination of everything the System was building toward. It is the Shadow Monarch Ashborn's power crystallized into a physical form — a dark, pulsing core of shadow energy. When Jinwoo absorbs it, his transformation from human vessel to true Shadow Monarch is complete. He gains the full, unrestrained power of the Shadow Monarch: unlimited shadow extraction, dimensional manipulation, and strength that rivals the Monarchs themselves. The Black Heart is not an item to be equipped — it's a succession. Ashborn's final gift to the vessel he spent eons preparing.
Also known as: The Black Heart, Black Heart, Ashborn's Heart, Shadow Monarch's Heart