Starseed

The Starseed is a powerful magical artifact featured in He-Man and the Masters of the Universe.

Filmation animated series
The Starseed was a small yellow sphere containing a portion of the power from the explosion which created the universe. Posibly the most powerful artifact on Eternia, it could grant any wish to it's holder. But the power was so immense that none except He-Man could control it without being corrupted. Only a few Cosmic Enforcers were aware of the Starseed's location.

Appearances

 * The Search

2008 Masters of the Universe Classics toyline
The Motu Classics line provided an expanded, alternate backstory for the Starseed:

A divine artifact taken from the Star Tree on Trolla, the Starseed was hidden by the gods in the core of Eternia. It's magic was so great that it seeped from the heart of the planet, giving rise to many powerful sorcerers on the surface.

The gods left the immortal giant Procrustus to guard the Starseed, but many would continue to seek it's power in the centuries that followed, including the Snake Men at the bidding of the Unnamed One. At one point, Hordak nearly split Eternia in two with the Spell of Separation in his efforts to obtain the Starseed.

Two great citadels were built over shafts leading to the Starseed and drew from it's power: The Central Tower and Castle Grayskull. The Council of Elders stored the Orb of Power within Grayskull to draw on the power of the Starseed. The Overlords of Trolla had created of Sword of He to harmonize with the magic of creation used by the gods, making it and the orb the only ways to harness the Starseed's power.

Much later, when the Unnamed One succeeded in obtaining the Starseed, it brought Procrustus to the surface and sparked a massive battle. The Starseed's fate after the conflict remained unclear, but it was likely returned by Procrustus to guard Eternia's core once more.