"More elements?!" Luna looked genuinely shocked. "I...I don't....I mean." She frowned thoughtfully. "I suppose it's possible. Sister and I found the original six over a thousand years ago. It's possible there are some that we missed. It was a very desperate time in our history, and we couldn't do a detailed search. As it was we just barely had enough time to find the original six and learn how to use them before our enemy Discord found us out. We had to strike as soon as he discovered us or he would have destroyed us. And afterwards, well, the Elements were put in our castle. We never did look for any others. There seemed no need."
She looked at Timber Crash. "As for Pestilence, whoever she was before had a weakness, like I did. The thing that possessed us both works like that. It finds something inside you where you feel weak or lonely, then it worms in. It pretends to be your friend and offers solution to your problems. But as soon as the crack is wide enough it slithers in and takes over completely, trapping the real you in your own mind. You can see, feel, and hear what its' doing but you can't respond. It used to gloat to me about how it did that to me, using my jealousy of my big sister and my loneliness when I thought that nopony liked my nights or me. So whoever Pestilence was before, she had some weakness in her heart that let the creature in. If we can find that we might be able to find who she was before. And if Dusk is right, maybe we can use these new Elements of Harmony to free her just as Twilight Sparkle and her friends freed me."