The Pit (March of the Machine Commander 63) - Common Magic: The Gathering Card

When you planeswalk to The Pit, each player creates their choice of a 3/3 white Angel creature token with flying or a 6/6 black Demon creature token with flying, trample, and "At the beginning of your upkeep, sacrifice another creature. If you can't, this token deals 6 damage to you."
Whenever chaos ensues, each player sacrifices a nonartifact creature of their choice.