This is a Doctor Who crossover (as if that wasn't already obvious), so if you don't like Doctor Who, why are you here?

This story ignores all canon past The Return of Harmony.

For years, the Time Lord known only as "The Doctor" has traversed throughout time and space, helping numerous beings out in the process. He's saved entire planets. He's defeated entire armies. But now comes the biggest challenge of all.

He has to travel with a pony of all things. Well, in any event, it's better than a Dalek or a Cyberman!