This card is very versatile and can be used on friendly AND enemy minions. That means it can be used as a removal, though not the best, and it can be used similar to Faceless Manipulator, though you'd need to sacrifice a minion for it. I believe it's pretty fairly balanced taking this into consideration.
Playing a Reno deck and you need a little more damage to close out the game but use up your one copy of Soulpriest? Use your Soulpriest for board wipe and need a little bit more damage? Playing Silent Priest in general? Your Doomsayer got silenced? Auchenai Shadowpriest is the card for you! Her ability will let you have at least 3-4 copies of Auchenai Soulpriest in your deck if you manage to have atleast one minion on the board. She's also good Arena because she will have the priest gain tempo and make healing cards more valuable while having a 5 mana 5/5 body. Having 5 Health and not having the effect herself, you can do the Circle combo and then heal her up to maintain the board.
For this week, I wanted to incorporate a little bit of synergy with Zoo. It can be played for tempo as a 2/3 or a 3/4 on turn 3, (depending on the status of your board), but could also be saved for when you have 6 minions and dropped as a 7/8!
As always good luck to everyone taking part this week!