The mini-set will contain 49 cards, excluding secret rares.
Card sleeves featuring Lillie will release alongside the set.
It seems the set will partly focus on Unova — N, Roxie, Reshiram, and Zekrom are featured on the booster pack. Unova was the only region that did not get a dedicated set during the Sun & Moon block, so perhaps this is their way of making up for it.
Could we also see a Dragon-type Reshiram & Zekrom-GX?
The set will probably become part of our SM12 set in November.