Kraji Crater

Comes into play tapped.
{t}: Add {1} mana to your mana pool.
{t}, sacrifice Kraji Crater: Search your library for
the Collectors Prison and put it into play. Shuffle
your library afterwards.
The Planeswalker Mordai retrieved the ancient artifact shaped as a sphere from the crater, after encountering the first six black projects combined
in the abominable planeswalkers hive.