Relentless Rats (M11) from Magic 2011, available at 401 Games Canada.

• Rarity: Uncommon
• Finish: Normal
• Artist: Thomas M. Baxa
• Card Text:
  Relentless Rats gets +1/+1 for each other creature on the battlefield named Relentless Rats.
  A deck can have any number of cards named Relentless Rats.