At only four ink to put down, and with a decent four willpower to keep her on the board in the early game, the benefits of including Belle in your deck far outweigh the costs
(Remove those cards from your deck before beginning a new game.) Watermark: League of Dastardly Doom Illustrated by Matt Cavotta Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Not Legal Modern Not Legal Brawl Not Legal Legacy Not Legal Comp
Honorable Mentions A lot of the most expensive Magic: The Gathering cards on Cardmarket are currently cards from the Holiday Release of Lord of the Rings: Tales of Middle-earth
As with any TCG game, there are a fair amount of erratas and rulings over M:TG's history, of course
Wizards with good enter effects are excellent here, like Sea Gate Oracle
Three mana Mana Rocks nowadays wont keep up with the speed of the format, unless there are some additional benefits on the table