Hey guys,
I have some feedback on the functionality of the Ranger feature: Horde Breaker that the ranger can take at level 3 when he takes the Hunter subclass. I understand we are in EA and many improvements are in store, but for the sake of giving my best feedback I'm going to address the feature as it stands. I will first explain the key differences between how horde breaker currently functions in 5e vs BG3, then I will explain why and how I believe the BG3 version should be improved and optimally implemented.

1. 5e version
2. BG3 version
3. 5e v BG3
4. Improvement ideas

1.
From the PHB 5e, the feat reads,
"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."

How the feat functions in 5e:
In 5e, the added attack from horde breaker can be applied from any weapon attack you make during your turn, regardless of whether or not it hits. This includes your regular attack, extra attack(Lvl 5), whirlwind attack(Lvl11), volley(Lvl11), bonus action attacks from twin weapon fighting or swift quiver(Lvl5 spell), and any other ways you may gain extra weapon attacks, for example haste. This does not include attacks of opportunity on other player's or enemy's turns. The added attack from this feature is not affected by action economy.
An example of how this works.

Thoughts:
This version feels very easy to use. You simply state to your DM after any attack that meets the criteria that you are going to make an attack using horde breaker. Sweet and simple.

2.
In BG3 the feat reads,
"Target two creatures standing close to each other, dealing X damage to the first target and open up the second for a followup attack."
The follow-up attack reads,
"Follow up on your horde breaker with a second attack. Deal X damage." "Prerequisite: Creature must be with 1.5m of first victim."

How the feat functions in BG3:
In BG3, when you select Horde breaker, 2 separate skills are added to your hotbar Horde Breaker(Ranged) and (Melee.) Using either skill allows you to make the correlating attack which consumes your action. The resulting attack will apply a condition(Horde breaker: creature is open to a follow-up attack) to any enemy near the target. This condition is applied regardless of whether or not the attack hits. After making your first attack, 2 more skills are added to your hotbar that are identical looking to the first two: Horde Breaker Follow-up(Ranged) and (Melee.) These are the the follow-up attacks that can be used once a turn against any enemy that has the horde breaker condition. While the initial use of the feat uses an action. The follow-up attacks are not affected by action economy.

Thoughts:
Having 4 skills on your hotbar for one feat feels very unintuitive. The follow-ups won't be permanently in the same spot unless you change settings to not forget memorized skills.
You use an action to attack with the specific skill Horde Breaker to get another attack. You can't use it when you make an offhand attack. This is worrying, but I'll get to that later.

**Personal anecdote: The way it is implemented made me originally assume it was broken and bugged, although that was a combination of how it works and user error. My hotbar filled up before my first use of horde breaker, so the follow-ups for the second attack appeared in my second hotbar, which I never went into as I'm a ranger and don't have a lot of spells. I also had no reason to believe that there would be 4 skills for one feat, so I just assumed it was bugged until i found the follow-ups later.**

3.
The difference between 5e and BG3.
Action economy. Horde breaker in 5e is intentionally kept away from all action economy. It is already a situational enough skill to use, so it is designed in a way that it will never prevent you from using it instead of something else. You can use in conjunction with your best attacks like lightning arrow, whirlwind attack, volley, and even with your bonus action attacks you get much later from swift quiver. As it stands in BG3, horde breaker has it's own skill that uses an action. Already this means that you can't use it with your offhand attack. This leads to some concerning questions. How are we going to use this with extra attack? How will we activate both whirlwind attack and horde breaker in the same turn? They are both actions. If you aren't able to use horde breaker in conjunction with these higher level attacks, then there is no reason to take it over Colossus slayer. Colossus slayer will already proc more often and won't compete in the action economy.

4.
How to improve the feat.
I understand that one feature, from one subclass, might not be worth putting the insane amount of effort that it may take to make it work like in 5e. With that said, I think there are varying different steps that can be taken to make this feat feel more intuitive. I will sort the different ideas I have to improve it into their respective levels of difficulty.

Level 1 - (cleaning up)
Functionally, everything will work the same as it did before. The only change will be that instead of having 4 separate skills on your hotbar, you will only have 2. This can be achieved by having the initial Horde Breaker(ranged) and Horde Breaker(melee) also trigger the corresponding follow-up attack when you reactivate it after you have made your first attack.

Level 2 - (more cleaning up)
We crunch the feat down into 1 skill. While you have your melee weapon equipped, your horde breaker(melee) will be on your hotbar. While you have your ranged weapon equipped, your horde breaker(ranged) will be on your hotbar. After activation and attack, the skill will trigger its corresponding follow-up upon reactivation until next turn.

Level 3- (toggle functionality)
Now that we have it down to 1 skill, instead of horde breaker skill itself initially being an action/attack, we can instead turn it into a toggle that will apply the horde breaker condition whenever the next weapon attack is made. It will apply either the ranged, main hand melee, or off hand melee horde breaker condtion. After the condition has been applied, a second attack can be made using whichever weapon was used to apply it. This will open up functionality that allows it to be used in conjunction with extra attacks, offhand attacks, and our big hitters later on.

Level 4- (adding horde breaker condition to every weapon attack)
Now that we have it down to a toggle functionality, we can change it to apply the condition to every weapon attack. Whichever weapon is used will apply it's condition of horde breaker(main hand melee, off hand melee, ranged) that can only be triggered while the corresponding weapon is out. The skill button itself no longer has to function as a toggle, that's done in the background. Instead it is only responsible for follow-up attacks. So when you use it with a bow, it will only be able to trigger on targets with ranged horde breaker conditions. When you use it while in melee, it can trigger only against targets with the main hand or off hand conditions. If they have both main hand and off hand conditions, i think for simplicity sake it would attack with your main hand.

TLDR
While the feat is mostly functional as is, the way it is currently implemented feels a bit clunky considering it adds 4 skills to your hotbar. It also loses some versatility that may not seem like a big deal at Lvl 4, but could be a substantial unintended nerf to its usability later on.