They increase the likelihood that Saruman wont trigger each turn and that Sauron will have something to reanimate when it hits the field
The low mana cost makes it viable in a wider array of decks than Fact or Fiction however the actual draw is worse being more easily disrupted and digging less far, not to mention devoid of a chance to get more than 3 cards
If you already know what order the sets launched in, working this out is easy: The First Chapter has a "1", Rise Of The Floodborn has "2" , and so on
Organize Your Collection and Enjoy It More The best way to organize Pokmon cards is the one that matches how you actually use your collection
In my opinion, EGAWA and Kouki Saitou absolutely RAN Crown Zenith with EGAWA's Golden Alts and Saitou's 9-card connecting set of Illustration Rares
Some Plots have static effects, some have "when this card is turned face-up" triggers, and some have both