Magnetrons are Silvers who can manipulate metalic elements.
"Magnetrons are elementals, able to manipulate different kinds of metal through rigorous training. More malleable metals like gold are considered easy to magnetrons, while only the most talented and powerful can hope to utilize complex, strong metals like tungsten and titanium. Magnetrons are considered valuable on the battlefield, as they can neutralize most metal-based weaponry, from missiles to bullets, resulting in the unique nature of Silver-led warfare. In Norta, the magnetrons of House Samos, led by Lord Volo, are a formidable family with great influence on the crown and kingdom." - On Silverblooded Abilities by Victoria Aveyard