During a Premier Draft my opponent cast a Guidelight Pathmaker and search for a Dune Drifter placing it on the battlefield. They were then able to reanimate a Possession Engine that cost 5 mana, despite the fact that the X value for Dune Drifter was 0. This allowed them to take possession of my Terrian Worldeater, swinging the game. This should not be possible because they did not cast the Dune Drifter to pay an cost.