The magus still hears the roar of the crowds. They're gone, but the will to compete remains.

Magus of the Arena

{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.

{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.)

Commander 2013

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