Curious Obsession is a uncommon Enchantment — Aura card from Rivals of Ixalan (RIX), collector number 35. Current market price: $0.39 (foil $1.95), TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature gets +1/+1 and has "Whenever this creature deals combat damage to a player, you may draw a card." At the beginning of your end step, if you didn't attack with a creature this turn, sacrifice this Aura.