Combat Research is a uncommon Enchantment — Aura card from Dominaria United (DMU), collector number 44. Current market price: $0.46 (foil $0.97), TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature has "Whenever this creature deals combat damage to a player, draw a card." As long as enchanted creature is legendary, it gets +1/+1 and has ward {1}. (Whenever enchanted creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {1}.)