Blizzard has kept the pack probabilities under wraps for the most part.

New Apple App Store rules could force Blizzard to disclose the drop rates for Hearthstone packs before players purchase them.

Recent controversy over loot boxes and in-game purchases appear to have prompted Apple to update the review guidelines for the App Store. The rules have been changed to include a clause requiring the drop rates for in-app purchases to be disclosed to customers.

“Apps offering ‘loot boxes’ or other mechanisms that provide randomized virtual items for purchase must disclose the odds of receiving each type of item to customers prior to purchase,” the rules now state.

It’s unclear if this would mean advertising it in game beside the purchasable item, or the developer simply making the information publicly available somewhere.

The change echoes similar moves by Chinese authorities earlier this year. The law, passed last December, meant that developers had to prominently publish the information and keep records of the details for government inspection. In May, Blizzard published drop rates for Hearthstone and Overwatch to comply with new laws requiring disclosure of the odds.

Related: Blizzard releases Overwatch loot box probability in China

The drop rates for Hearthstone released in China showed a 20 percent chance of an epic in a pack, and a five percent chance of pulling a legendary. Every pack includes at least one rare or better.

Given that Hearthstone in China is distributed by a third party, and kept generally pretty firewalled from the rest of the world, it’s possible these odds are different outside of the country. These new App Store rules and the disclosure required could either show any difference, or confirm that those odds apply worldwide.