Control Priest is a long-time archetype in Hearthstone. It has come and go in many forms, and has usually been on the weaker side of the meta. This changed in The Witchwood where a version with Mind Blast became popular and is sometimes literally referred to as Mind Blast Priest.
Now that The Boomsday Project expansion is here, the deck has continued to be a solid option for the class. It didn’t get much in the way of new cards, but it’s able to utilize Giggling Inventor as a way to stall into the late game so it can get to its powerful Mind Blast combo.