Sac Engine anyone?

Spells cost less to cast.

Buyback costs cost less.

Whenever a creature enters, you lose 1 life and add .

Buyback (You may pay an additional as you cast this spell. If you do, put this card into your hand as it resolves.) Return the top creature card of your graveyard to the battlefield. That creature gains haste until end of turn. Exile it at the beginning of the next end step.

Black spells you cast cost less to cast.