I give it to onslaught.....I got this quote from nationalgeographic.com of all places...lol
"Without question, Magneto—the mutant who controls the power of magnetism [in the X-Men series]—is the most powerful villain in comics," Weinberg said. "Electromagnetism is the most powerful of the four basic forces of the universe."
But Magneto rarely uses his superpowers to cause maximum damage. Theoretically, everything on Earth that involves electricity falls under his influence. Instead, Magneto generally uses his powers to do things like manipulating the iron content of blood to establish mind control over others.