Books like The Fate of Ten

For years the Garde have fought the Mogadorians in secret, but now the invasion has begun. If the Garde can't find a way to stop the Mogs, humanity will suffer the same fate as the Lorien: annihilation.When the Elders sent the Garde to Earth, they had a plan-one which the Garde are finally starting to understand. A group of the Garde travelled to an ancient pyramid in Mexico where they awoke a power that had been hidden for generations. Now this power can save the world or destroy it. It will all depend on who wields it.