Hearthpwn

Card rarity is just a way to make more money through dust, aside from legendary because they are limited to 1 per deck. Rarity used to be used for the "complexity" of a card but that doesn't hold true anymore, the only place it matters is arena drafting (which could be done on a card-by-card basis anyway).

From the recent set alone: Mistake, Crystal Broker, Hawkstrider Rancher, Vile Apothecary, Prismatic Elemental, Underking. There is nothing complex about these cards that needs any deep thinking to find their applications and decks.