Children of the Elementi by Ceri Clark
Great story of good versus evil, but with a different twist.
Taking their strengths from nature, fire, wind, water and earth, plus one unifying force, 5 people from different dimenstions join together to combat another power looking to take control. These 5 have never met before, seeing as how their homeworld was destroyed many years earlier. These 5 are direct descendants of the original owners of the crystals, each with it’s own ability. They were scattered in the hope of reuniting to join their forces to bring the Elementi back in control, away from the Magi.