Well, Shadowborn Demon lets you have your fun, but also keeps it bloody good while you slaughter one of your opponent's creatures and enjoy immunity yourself because of the creatures you've already sacrificed
Scythe of the Wretched Scythe of the Wretched hails from the first iteration of equipment in the Mirrodin set
For example, Rise of the Floodborn added a simple Amber synergy with the Seven Dwarfs characters, half of which are Common cards, who support other Dwarfs characters in various ways
In my personal color pie opinion, Lurrus of the Dream-DenLurrus of the Dream-Den isn't a black card in any fashion, and should just be a mono-white card anyhow (a mono-white card that would be up there with Teshar, Ancestor's ApostleTeshar, Ancestor's Apostle in power level, only it could be a Companion in any mono-white deck)
This card is a really fun commander to build around and play, but its really hard to place it in the 99 in any other deck because of its abilities
And Deadly Brew returns a permanent card from the graveyard to hand when each player sacrifices a creature or Planeswalker