Swallowtail Butterspy is a Common Effect Monster card from Yu-Gi-Oh! (War of the Giants Reinforcements, WGRT). Current market price: $0.10.
Common
War of the Giants Reinforcements (WGRT)
Card Text
When another monster you control inflicts battle damage to your opponent: Target 1 face-up monster your opponent controls; it loses ATK equal to the battle damage inflicted.
