Shattered Mirror

The Large Prismic Black Monolith (known by the Great Beings as the Shattered Mirror) was a device created by a dying Great Being known as Okk. It allowed travel between alternate dimensions. It was indestructible as it was a fixed point in time and space, until wibbly-wobbly timey-wimey stuff happened and it went kaput.

The Shattered Mirror Universe versions of Ta'harok and Kakamu are known to have had emerged from it on the planet Chenrotoss.

Somehow, it appeared on the same planet as Atlantis. Some beings came through it and kidnapped Trantoshen.

After it was destroyed, SM Trantoshen, back in his own universe, built the Shattered Mirror II as a means of gaining access to the main multiverse again. It worked.