[The spell is simple and complex all at once. Simple because it is merely analysis and telekinesis -- understanding the presence of, stresses in, and limits of the rock, then lifting it into that formation. Complex because both components require an incredible amount of finesse and skill to do all of that so casually.]

Pony magic is not necessarily so complicated, I think. We cast spells by transforming mental energy into magical energy through our horns. But to do so, we have to very carefully pattern the mental energy first to achieve the desired results.