Would this not just be bananas in Big Priest? Their deck is, like, 25 spells and 5 minions. Easily a 1-of in big priest, I would say... possibly even two. 7 mana resurrect an Obsidian Statue, Ysera, and Lich King seems good. Even if barnes was one of the 3, it would still be good.
Let's Analyse this, the only resurrect card for priest in standard for now is Eternal Servitude which costs 4 mana and summon only 1 minion ( Discover )
And this spellstone costs 7 ( 1 less mana if we cast double Eternal Servitude ) and we summon 2 minions ( first version ) that's already better than Eternal Servitude ,getting the first upgrade can be done so easily with big priest, 7 mana get 3 minions back? that's what big priest was missing, more resurrect cards, i voted Very good.
even the baseline of summon two is decent, but I think this is too expensive to play and hard to upgrade. Eternal Servitude is played because of the ability to cheat out early minions and then resummon them in the early game with it. Also, you actually get to choose which minion you summon with that card.