Magneto, Master Of Metal

Flying, Ward {2}

Whenever Magneto or another Mutant you
control enters, if you cast it, discover artifact X,
where X is its mana value minus one. (Exile cards
from the top of your library until you exile a
nonland artifact card with mana value X or less.
Cast it without paying its mana cost or put it into
your hand. Put the rest on the bottom in a random
order.)