略(りゃく)取(しゅ)者(しゃ)の戦(せん)利(り)品(ひん)

Seek a nonland artifact card with mana value X or less and put it onto the battlefield. If a card with mana value less than X is put onto the battlefield this way, this spell perpetually gains "This spell costs more to cast," then return this spell to its owner's hand.