"Ah. Well, the one that gave me wings was difficult enough that dear Twilight could only cast it on me, giving me the most lovely iridescent wings you can imagine. As she's the most magically talented unicorn I know, if Twilight struggled with it, then it must be a very difficult spell indeed. The cloud-walking spell was quite a bit easier, from what I understand, though it's not a spell I can cast myself." 