I'm unsure about this card. If priests get more impactful spells this could be really good. Being able to have upwards of 4 copies of a spell in a deck seems like it could be really really good. Pretty cool design but I'm not sure if it fits well in priest and I'm not sure how good it will ultimately end up being. I voted playable.
Not sure if this will be good enough for Constructed, but for Arena different story...Very good Arena card, allows you copy the most powerful spell option and one you believe you'll need or currently need.
Strong in a Reno Priest list, where'd you'd love to have 2 entombs/sw:d/dragonfire/etc.
And discover is great since the pool of cards is so small to choose from and you have complete control of what could come up. For example: add in a Greater Healing Potion, then discover it to have 2 against Pirate Warrior.
Won't see a ton of play, but has its uses for sure.
Only issue is that it will only work in wild with Thaurissan. Plus, we already pretty much had that in standard (Embrace the Shadows + Flash Heal + 2 Mind Blasts) and nobody used it. I guess it's one more tick of Thaurissan but still any reliance on Thaurissan for more than one card tick can be painful.
I'm hoping for some sort of aggro priest shenanigans but many of the best tools (Shadowbomber, inspire guy) are in wild. Still might be doable though depending on what we get. Two of these discovering two more Mind Blasts means good pressure to your opponent's face.
Priest traditionally has card draw problems, especially in situations when Priest desperately needs AoE against Hunter/Warrior/Shaman/Paladin/Zoolock or target removal cards against Rogue/Mage/Druid.
Most Priest decks are very reactive, and being able to draw the card that you need mid-game is very important for this class.
If you play Priest often enough, you know what I mean. I think this is a good card. I really enjoy how Blizzard emphasizes on card draw for Priest in this expansion as this is one of Priest' main weakness in every deck.