Contagion Clasp (DDF) from Duel Decks: Elspeth vs. Tezzeret, available at 401 Games Canada.

• Rarity: Uncommon
• Finish: Normal
• Artist: Anthony Palumbo
• Card Text:
  When Contagion Clasp enters the battlefield, put a -1/-1 counter on target creature.
  4, T: Proliferate. (You choose any number of permanents and/or players with counters on them, then give each another counter of a kind already there.)