Rarity defeating a lightning-flinging demon, using only low-grade telekinesis and her Dowsing Device spell.
And later, disabling another by using a hairstyling spell to tie her Razor Floss hair into a bun.
Derpy is a spy. Not the "cloak-and-dagger" assassination spy, but an informant-type spy. She's a mailmare, you'd see her everywhere and all the time. You start to subconsciously ignore her...which gives her the perfect opportunity to eavesdrop on any secret conversations you might be having...