The Rotation Select Pack will be available in the Shop for 1,000 crystals per bundle starting from the v4.0.0 update. This 10-card-pack bundle will only include cards in Rotation from Neutral cards and cards from the class you select. The tenth pack has a guaranteed legendary card.
The Rotation Select Pack can be purchased from Shop > Buy Cards > Buy Packs. It can be purchased up to 3 times per account using crystals only, and will be available until the release of the next card set. Draw rates can be checked from the card pack purchase screen.