Dr. Boom's Puzzle Lab, the series of singleplayer puzzle challenges announced last week for the Hearthstone expansion The Boomsday Project, is now open to all.

Each of the four labs starts off simple, but the tasks quickly ramp up in difficulty. You can take them on in any order you like, though, so you can veer off to something else if you get stuck. Clearing them all will get you some face-time with Dr. Boom himself—and a Boomsday card back, if you're able to match his wit. And even if you don't get that far, you'll get three free Boomsday Project card packs just for logging in. Full details are up at playhearthstone.com.