Lurrus of the Dream-Den is a rare Legendary Creature — Cat Nightmare card from Pioneer Challenger Decks 2021 (Q06), collector number 9. Current market price: $3.23, TCGplayer market prices via Scryfall.
Companion — Each permanent card in your starting deck has mana value 2 or less. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.) Lifelink Once during each of your turns, you may cast a permanent spell with mana value 2 or less from your graveyard.