Spiked Ripsaw (DBL) from Innistrad: Double Feature, available at 401 Games Canada.

• Rarity: Uncommon
• Finish: Normal
• Artist: Jesper Ejsing
• Card Text:
  Equipped creature gets +3/+3.
  Whenever equipped creature attacks, you may sacrifice a Forest. If you do, that creature gains trample until end of turn.
  Equip 3 (3: Attach to target creature you control. Equip only as a sorcery.)