You need to understand grading nuances, track PSA population reports, monitor competitive play trends, follow which cards are hot or cooling off, and stay current on reprints and new releases that might impact values
They essentially allow for an extra land drop when in an opening hand, and allow for early ramp that is reusable the entire game
This lets you set one or more of your opponents back, preventing them from interacting with you during your turn since they won't have land to use
and finally Exodia, the Forbidden One, a legendary card that lets you win if you get all five parts in your hand, as shown during the first duel between Kaiba and Yugi in the anime
The Convoke ability makes it sometimes free, which increases the odds that you'll be able to play this, plus your own boardwipe, in the same turn