Gluttonous Slug (MH1) from Modern Horizons, available at 401 Games Canada.

• Rarity: Common
• Finish: Normal
• Artist: Greg Staples
• Card Text:
  Menace
  Evolve (Whenever a creature enters the battlefield under your control, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)