Goblin Spellcaster

{1}{u}{r}, {t}, Discard a card: Exile the top card of your library. Until end of turn, you may cast a card you own in exile whose text box contains twelve or fewer words of rules text without paying its mana cost. (Numbers or groups of numbers, i.e. +1/+3, 2, etc. count as one word, and mana symbols and reminder text doesn't count.)