Yona, Caretaker of the Zora

This spell costs {1} les to cast for each artifact you control.
When Yona, Caretaker of the Zora enters the battlefield, put the top four cards of your library
into your graveyard.
{t}: Choose target artifact card in your graveyard.
You may cast that card this turn. (You still pay its
costs. Timing rules still apply)