Praxan's Siege Lab

At the beginning of your upkeep, you may pay {x}. If you do, you may search your library for a vehicle with converted mana cost X or less and put it onto the battlefield.
{5}{b}{r}{t}, Search your library for a artifact card and put it onto the battlefield. Activate this ability only if you control a creature named Praxan, Scourge of Enemies.