Each card in the deck must differ from each other card in the deck in at least one of the following: Name, Pokmon Type, HP, Retreat Cost, Weakness, Resistance, Ancient Trait, Ability, Pokmon Power, Pok-Power, Pok-Body, or Attack (where attack cost and base attack damage are considered a part of the attack), with the following exceptions: You may include any number of basic energy cards with the same name
That means that Thousand-Eyes Eidolon's name doesn't "change" to Thousand-Eyes Idol
************IMPORTANT************
If you control Training Grounds and you activate the ability with X equal to 5, you'll have to pay only
Back in October, Good Morning Magic presenter Gavin Verhey also revealed that the Stranger Things cards are "not intended for competitive constructed play", but rather targeted at collectors, and Commander players
This makes them well-suited for decks that focus on controlling the battlefield and slowly grinding down opponents