If a card's Cost exceeds your Duelist Level, you can't use that card AT ALL until you level up
As more collectors become aware that Japanese cards are often better centered and higher quality, demand has increased, pushing prices up
The first section, above the type line, contains their chapter abilities, and the second section, below the type line, contains any other abilities (or italicized flavor text)
However Rotpriests ability doesnt care who targets your creatures, allowing you to fire off multiple, cheap spells and win the game
Theres almost certainly potential to mix and match the decks, building something you could take to play at a casual event, but it seems the next logical step is to consider the range of Structure Decks to help learn about deck construction and theming
Also in the realm of random but rare cards, I also pulled a Scovillain ex Ultra Rare