If you don't cast it, put it on the bottom of your library
The most expensive cards in 151 feature several cards of the starter Pokemon and their evolutions, like this Squirtle on a beach
I don't know if we can bank on a 2/2, and my early testing showed me that sometimes you want to pay GGG1 for Viscera Seer and just be done with it
Thankfully, this slot is perhaps the most flexible for opting for a replacement of the effect
For instance, Umbreon ex has an attack costing one Darkness, one Lightning, and one Psychic energy, while its counterpart Espeon attacks with Grass, Psychic, and Darkness energy
This list is chock-full of some incredibly valuable cards that debuted in 2024, almost all of which came from Collector Boosters, the extremely pricey booster packs that are made for devoted collectors (and investors)