Crop Rotation, Deadly Rollick, Culling the Weak, Diabolic Intent, Phyrexian Altar, Ashnod's Altar, and Phyrexian Tower all play a big role in how the deck takes shape, creating several loops where creatures are sacrificed for benefits like infinite ETBs, death triggers, mana, and so on
Elven Farsight Turn one scry three then potentially draw a card
4 Pete - Games Referee 195/204, Steel Pete - Games Referee isn't a card that's going to win a game on its own, but it could certainly stand in the way of losing
Deckbuilding is an important part of any TCG, so once you've tried out these options don't be afraid to make further alterations until the deck feels good to you.
Three Dog, Galaxy News DJ Drawing cards in Boros feels every bit as good as it does in Black and Red