0 bills: Personally I tried with 0 bills for a longer period of time and you need more luck than I would prefer to set up good enough
The 3-cost Black Sorcery Buried Alive is, er, brought to life in Bring Out Your Dead - because why shouldn't we use the corpses of medieval plague victims to fuel necromantic Black spells
Its powerful abilities make it a dangerous threat in Commander and casual play
Sure, they get sacrificed at the end of turn, but do you care when a pile of Combustible Gearhulk copies, or Inferno Titan duplicates, already left your opponents in ashes
There are cases where you want to bounce your own permanents instead
Due to them only starting the TCG recently, they decided to create their own sets entirely by combining multiple sets