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
Is it the Conkeldurr Alternate Art
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
Ramp is fine, but when youre already able to generate five mana, tacking a limited Rampant Growth onto all of your creatures isnt going to help you out all that much
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
Trigger Happy This two-cost uncommon Red instant will copy a triggered ability of any target permanent and you control it