Bontu's Monument

Black creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, each opponent loses 1 life and you gain 1 life.

Ozox, the Clattering King

Ozox, the Clattering King can't block.
When Ozox dies, create Jumblebones, a legendary 2/1 black Skeleton creature token with "This creature can't block" and "When this creature leaves the battlefield, return target card named Ozox, the Clattering King from your graveyard to your hand."

Phyrexian Altar

Sacrifice a creature: Add one mana of any color.