Magneto, Unstoppable

Flying, protection from artifacts

Metalcraft — As long as you control three or more artifacts, all non-creature artifacts you control are creature artifacts with base power and toughness 4/4.

{3}{w},{t}: Create a 4/4 colorless Sentinel artifact creature.
{2}{u}{u},{t}: Gain control of target artifact.
{b}, Sacrifice an artifact: You draw a card and lose 1 life.
{1}{r},{t}: Destroy target artifact. If you controlled that artifact, it deals damage equal to its mana value to any target.