Contaminated Bond is a common Enchantment — Aura card from Mirrodin (MRD), collector number 61. Current market price: $0.11 (foil $0.40), TCGplayer market prices via Scryfall.
Enchant creature (Target a creature as you cast this. This card enters attached to that creature.) Whenever enchanted creature attacks or blocks, its controller loses 3 life.