Priest of Gix

When Priest of Gix enters, add {B}{B}{B}.

Sol Ring

Stitcher's Supplier

When Stitcher's Supplier enters or dies, mill three cards. (Put the top three cards of your library into your graveyard.)

Jet Medallion

Black spells you cast cost {1} less to cast.

Chthonian Nightmare

When Chthonian Nightmare enters, you get {E}{E}{E} (three energy counters).
Pay X {E}, Sacrifice a creature, Return Chthonian Nightmare to its owner's hand: Return target creature card with mana value X from your graveyard to the battlefield. Activate only as a sorcery.

Mausoleum Secrets

Undergrowth — Search your library for a black card with mana value less than or equal to the number of creature cards in your graveyard, reveal it, put it into your hand, then shuffle.