Beorn's Hospitality is a uncommon Enchantment card from The Hobbit (HOB), collector number 120. Current market price: $0.26 (foil $0.33), TCGplayer market prices via Scryfall.
Landfall — Whenever a land you control enters, put a +1/+1 counter on target creature you control. {5}{G}{G}: This enchantment becomes a Bear creature in addition to its other types and gains "This creature's power and toughness are each equal to the number of lands you control." (This effect doesn't end.)