Lumra, Bellow of the Woods is a mythic Legendary Creature — Elemental Bear card from Bloomburrow Promos (PBLB), collector number 183p. Current market price: $27.17 (foil $26.54), TCGplayer market prices via Scryfall.
Reach, vigilance Lumra's power and toughness are each equal to the number of lands you control. When Lumra enters, mill four cards. Then return all land cards from your graveyard to the battlefield tapped.