Shadow Crystal



The Shadow Crystal is a crystal of dark magic in Twilight Princess.

Location
After completing the Lakebed Temple, Link and Midna arrive at Lanaryu's Spirit Spring, where they are confronted by Zant, who curses them both when Midna refuses to help him. Zant summons the Shadow Crystal and, in response, Wolf Link attacks, only to have the Crystal forced into his forehead, leaving Link trapped in his Wolf state.

Deep within the Sacred Grove lies the Master Sword, which Link and Midna finally find after following the Skull Kid. As Link approaches the sword he transformed back into his human form; the curse of the Shadow Crystal is broken, and it coalesces in Midna's hand.

Uses
By using the power of the Shadow Crystal, Link gains the ability to transform into wolf form at will, as well as use Twilight Portals to teleport great distances.

As it turns out, the Dark Fog that hinders Link's progress in the Palace of Twilight is also comprised of Shadow Crystals.

Trivia

 * Midna states that the shadow crystal is "different from our tribes' shadow magic.", implying that Zants' power is really Ganondorf's magic.