Approach needs to be cast twice for you to win, and it has seen play as a win condition in control decks with lots of filtering, card selection, and scry/surveil effects
However, if I did start a master set (maybe once the price tide lowers), my first purchase would be Ethan's Ho-Oh ex #230 , an SIR so gorgeous and full of nostalgia that I almost spent all my money on Destined Rivals anyway
The Primal distinction is currently limited to Kyogre and Groudon, but each Pokemon boasts a handful of distinctly valuable Primal cards
Gandalf the White [Foil] #19 Magic Lord of the Rings Keep track of your collection value over time
Some of these cards, like limited edition cards, shiny Pokemon, and so on, are extremely valuable and command high prices, but it's important to make sure you that you're purchasing old or used cards from reputable dealers when shopping online