The Everfree Forest is ancient, carrying within its soil and roots an untold amount of untapped magic. It can be felt by every pony, from the elder alicorns to the untrained earth ponies. Tangible and deep, possibly unending. There is, however, a very good reason no pony has ever successfully used this power.
It isn't their forest.
Story ten in my Twidash Challenge: Crossover Theme
Image by me. Screenshot for "The Secret of Kells"