https://www.gamespot.com/articles/hearthstones-boomsday-project-bundles-are-an-exper/1100-6460731/

Hearthstone's next expansion, The Boomsday Project is coming on August 7. Pre-order bundles are already available at two different tiers, but fans quickly noticed that these bundles are different than the last edition, The Witchwood. Blizzard chalks it up to experimenting with different bundle types to see which ones resonate the most with players.

For context, most expansions have offered a pre-order price of 50 packs for $50, plus a special card back. The 1-pack-per-dollar ratio is better than the standard bundles that are available year-round. The Witchwood threw in 20 bonus packs, bringing it up to 70 packs for $50.