Talk:Twilight's Kingdom - Part 2/@comment-26973802-20140510173526/@comment-11677914-20140510200754

@Alysdexia - didn't Celestia explained soo? Tirek had to start draining energy from unicorns and only when he had enough power, he could start taking the energy from pegasi and earth ponies (and alicorns). This means that Tirek has, when weak, only the energy to drain magic from creatures where the magic can "get to the surface", unicorns' horns as this is their direct "device" to use magic, while earth ponies and pegasi do not have that, their magic might be locked deeper in them. Idem dito for Cerberus, if he has magic at all (Tirek takes magic, not strength).