As Celestia takes a leisurely flight across a rather mountainous region of equestria, she notices a purple glow coming from a cave on the side of a mountain, When she enters she is invited by floors, walls and ceilings made of squarely cut blocks of a strange stone with purple lines of what looks to be some sort of energy flowing through it, she calls the mane six to come look at it, and call upon them to find out what it is and what it's purpose was. The ponies accidentally trigger a teleportation sequence teleporting them to the eridian ruins in caustic caverns on pandora.