Favored Enemy is a rare Enchantment card from Alchemy Horizons: Baldur's Gate (HBG), collector number 66.
As this enchantment enters, note the most prevalent creature type in an opponent's library. When this enchantment enters, target creature you control fights up to one target creature you don't control. Whenever a creature an opponent controls of the noted type dies, put a +1/+1 counter on target creature you control.