they CAN work but they require a different set up.
Exactly
Favored Enemy
Beginning at 1st level, you have significant experience studying, tracking, hunting, and even talking to a certain type of enemy.
You gain one of the following features of your choice.
Banisher
You are a bane to those not of this world. When you score a critical it against an aberration, celestial, elemental, fey, fiend, or undead, you deal an additional 1d12 damage.
Colossus Slayer
Your tenacity can wear down the most potent foes. When you hit a creature with a weapon attack, the creature takes an extra 1d8 damage if it’s below its hit point maximum. You can deal this extra damage only once per turn.
Giant Killer
When a Large or larger creature within 5 feet of you hits or misses you with an attack, you can use your reaction to attack that creature immediately after its attack, provided that you can see the creature.
Horde Breaker
Once on each of your turns when you make a weapon attack, you can make another attack with the same weapon against a different creature that is within 5 feet of the original target and within range of your weapon.
Lone Stalker
Seclusion sharpens you ire. When you hit a creature with a weapon or Unarmed strike, you deal an additional 1d10 damage if there are no allied or hostile creatures within 20 feet of you. You can deal this extra damage only once per turn.
Man Catcher
Your weapon attacks and unarmed strikes against giants and humaniods score critical hits on a roll of 18, 19, or 20.
When you gain this feature, you also learn one language of your choice.
You choose one additional favored enemy feature and an associated language, at 6th and 14th level. As you gain levels, your choices should reflect the types of monsters you have encountered on your adventures.