Beast Whisperer can be a real game changer for you whenever it is in play
Build your army of mindless androids alongside commanders Szarekh, the Silent King and Imotekh, the Stormlord. The Necron Dynasties deck brings a ton of goodies for black deck fans, and for me personally Trazyn the Infinite is at the top of my list
Peer into the Abyss is another great card to abuse with Rowan, and honestly the list just goes on
Red + White Burn tends to alter combat and/or provide life (Boros Charm, Lightning Helix, Intimidation Bolt, Aurelia's Fury, etc.)
You can pay one black mana and sacrifice six creatures that all share the name Shadowborn Apostle to search your deck for a Demon creature card, put it directly into play, and shuffle your library
If either creature is an illegal target as Beastie Beatdown tries to resolve, the creature you control won't deal damage