It is the 7th Core Booster of Series 12, following Rage of the Abyss
My guess is that they wanted to emphasize that cards with descend care about permanent cards in the graveyard
The cards are selected so that there is one of each original rarity: Rare, Super Rare, Ultra Rare, and Secret Rare
When a card or effect that would inflict damage to you is activated, while this card is in your GY (except during the Damage Step): You can Special Summon this card, and if you do, make that effect damage to you 0
Wait and see what it's for!" It's possible that these will be in some way linked to the as-yet unreleased Pokemon TCG Pocket trading mechanics, though that's speculative at this time
#2 Vaporeon (Master Ball Pattern) Set: Prismatic Evolutions Increase: +$23.10 Current Market Price: $44.30 All the Master Ball Pattern Eeveelutions from Prismatic Evolutions have spiked since April