As someone who pretty much exclusively played Cyclone Mage in the Rise of Shadows meta, and then swiftly moved on to Highlander Mage once Saviors of Uldum launched, I’ve won my fair share of games thanks to Luna’s Pocket Galaxy. For those that don’t follow Hearthstone closely, the card is a Legendary spell that drops the cost of all minions remaining in your deck to one mana. This means if you can find the space in a game to spend five mana doing nothing, you can then highroll into a series of big bombs that now cost one mana. It’s a ridiculous card, but funnily enough, when it was first introduced into the game it cost seven mana and saw next to no play. In the Rise of the Mechs event, however, its cost was reduced to five (alongside a bunch of other buffs) and it quickly made its presence felt.
Source: IGN.com Pro Hearthstone Players on Why Luna’s Pocket Galaxy Needs to be Nerfed