Well, this is quite a low varience card. I would compare it with shifting mass. Shifting mass has a good chance to hit a rare card, since rares have often a higher cost. But very often shifting mass hit an uncommon wich is not that great in cost to effect ratio, but hasjust a higher cost. And i didn't began talking about zero cost cards. This card would in most cases hit a rare card for sure.
So, while i like the idea, it's just too easy to use. All common cards which can summon rares have either a high varience (mage school, shifting mass) or are bound to more advanced conditions(golden Staff, magic lamp, necromancy). So i would add a condition like "if new, else summon highest rarity non-rare card" (like book of Nature) or something different, more interesting