Due to the official in-app announcement, the 1st booster, The Ultimate Rising, and the 2nd booster, Age of Discovery, cannot be purchased after February 15. Get cards you need as soon as possible although the announcement says cards contained by those packs will be obtainable again in future event or card releases.
The Ultimate Rising contains many cards that can play their role in any kinds of decks, such as Sphere Kuriboh and Wonder Balloons. If you plan to do reroll, I strongly recommend you to get a copy of Sphere Kuriboh from this expansion.
On January 1st, a banner describing "New card box, Valkyrie's Rage, has been added" had appeared In Japanese App Store. It seems that was an accident since the banner was replaced with another one mentioning "Neo-Impact", the card box that had been released recently.