Put any number of target artifact cards from your graveyard on top of your library.
Draw a card.
You can cast this with zero targets. If you do, you’ll get to draw a card. However, if you cast this with at least one target and all of those targets become illegal (because another effect has removed them from the graveyard, perhaps), the spell won’t resolve and you won’t get to draw a card.
You choose the order of the cards you put on top of your library.