The names of expansion packs and themes of the card design mean that each card and set has its own story and narrative. Despite the recent popularity of trading cards games such as Magic: the Gathering and Star Realms (my TCG of choice), the Pokmon team are as content today balancing cards and game mechanics as they have been for the last two decades
If you read the rumor sites, there are a few popular theories
Play cards featuring fan-favorite characters, and battle with iconic monsters like beholders, mimics, mind flayers, andof courselegendary dragons
Officially, it is not part of a block
Basic lands also work well for this since they have minimal text and lots of open space
Feaster of Fools has convoke (you can tap creatures to help pay its mana cost) and devour 2 (sacrifice any number of creatures to add twice that many +1/+1 counters to it): Demonlord Belzenlok has an ability that causes him to put cards in your hand for the small cost of 1 damage to you per card