Purah, Sheikah Engineer

{4}: Reveal cards from the top of your library until you reveal an artifact card. Put that card onto the battlefield, then add one mana of any color for how lower it's mana cost is to 4. When it enters the battlefield, you may pay {2}. If you do, Activate it.
{t}: Draw 2 cards.
{3}: Untap Purah, Sheikah Engineer.