Porphyry Nodes (TSR) from Time Spiral Remastered, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Alan Pollack
• Card Text:
  At the beginning of your upkeep, destroy the creature with the least power. It can't be regenerated. If two or more creatures are tied for least power, you choose one of them.
  When there are no creatures on the battlefield, sacrifice Porphyry Nodes.