Gideon's Intervention is a rare Enchantment card from Amonkhet (AKH), collector number 15. Current market price: $0.26 (foil $0.46), TCGplayer market prices via Scryfall.
As this enchantment enters, choose a card name. Your opponents can't cast spells with the chosen name. Prevent all damage that would be dealt to you and permanents you control by sources with the chosen name.