Legendary spells are a brand new addition to Hearthstone for the next expansion—and from what we’ve seen so far they’re going to be pretty powerful.

The Boomsday Project is now just seven days away. Next Tuesday every class gets one of these bonkers legendary spells.

Luna’s Pocket Galaxy is a seven mana Mage spell. When it’s played, it changes the mana cost of all the minions in your deck to one mana.

The effect of this spell is absolutely crazy. Minions that are as expensive as ten mana or higher will cost just one mana once this is played. But it’s pretty high variance—if you draw this right at the bottom of your deck, you’ve probably got a bunch of expensive minions to play beforehand.

Much like Frost Lich Jaina, this is an all-in strategy for Mage—draw it and win, don’t draw it and lose.

The Boomsday Project is the second expansion of the current Standard year, the Year of the Raven. It will add 135 new cards to the game, including new keywords like Magnetic. It is currently available to pre-order, with all the cards becoming available on Aug. 7.