Judgment includes a cycle of common one-mana creatures (or, as R&D calls them, a cycle of "C" creatures… "C" means "a colored mana") that each can be sacrificed to produce an effect. They are: Dwarven Scorcher, Cabal Trainee, Hapless Researcher, Benevolent Bodyguard, and Krosan Wayfarer. (You can click on those card names to read the cards if you don't know what they do.)
This is not the first time such a cycle has been attempted. Back during Tempest design, a similar cycle was submitted. But it never bore out -- the green, white, and blue ones were cut during development. The ones that stuck? Mogg Fanatic and Blood Pet.