Gladiatorial Arena

{t}: Add {r} to your mana pool.
At the beginning of your upkeep, target creature you control fights target creature you do not control. If a creature dies from this effect, the controller creature that did not die puts a colorless artifact token named Gold on the battlefield that reads "Sacrifice this artifact: add one mana of any color your mana pool."
The pits of Dumar hold the greatest riches for those who know their gladiators.