Suggested by Sonic Mirror Master is easily one of the most powerful Flash villains and I always liked how unique his power set is. It would be difficult for Orion to catch him initially because of all the mirrors but Orion has the power to level the planet if he keeps going. Mirror Master will run out of places to hide eventually and the main problem here is really the fact that at the end of the day he has no real way to hurt Orion. Orion wins.