Son Gohan, the Empowered (Gold Stamped) (P-377) [Promotion Cards] Cat Nightmare Beast if your Leader Card is

if your Leader Card is mono-green and your opponent has 7 or more cards in their hand : Play this card from your hand with a marker on it

Set: Eventide Type: Creature — Elf Druid Rare Cost: {1}{G} {T}: For each color among permanents you control

Set: Arcane Rising Unlimited Edition: Unlimited Finish: Rainbow Foil Type: Instant Rarity: Majestic Class: Generic Cost: 1 Choose 2

its owner shuffles his or her graveyard into his or her library

They just know

Son Gohan, the Empowered (Gold Stamped) (P-377) [Promotion Cards] Cat Nightmare Beast if your Leader Card isSet: Promotion Cards Rarity: Promo Color: Yellow Card type: Unison Power: 5000