Mystery Booster 2

Arena

{3}, {T}: Tap target creature you control and target creature of an opponent's choice they control. Those creatures fight each other. (Each deals damage equal to its power to the other.)

Magic Online Promos

Time Spiral Timeshifted

{3}, {T}: Tap target creature you control and target creature of an opponent's choice he or she controls. Each of those creatures deals damage equal to its power to the other.

HarperPrism Book Promos

o3,oc
T: Choose one of your creatures and have your opponent choose one of his or her creatures. Both target creatures become tapped. Your creature does its power in damage to your opponent's creature, and your opponent's creature does its power in damage to yours.