If you’ve read 2K’s excellent write up of How Scoring Works in Battleborn’s Story Mode (if you haven’t I highly recommend reading up on it first), you will know that to get the best possible star rating score in any given mission you will need to kill enemies within a certain amount of time to trigger a Quick Kill Bonus. Triggering a Quick Kill Bonus can reward you up to 4x (or possibly more) the amount of score you would normally receive upon killing an enemy so it is definitely worth getting a handle on the mechanic.
Since the official guide didn’t get too nitty gritty about this, I decided to go looking for more information by doing a bit of data mining on the PC version of the game.
First off, all enemies can be broken into 5 tiers.
- Popcorn
- Basic
- Elite
- Champion
- Boss/Unique
Popcorn & Basic
Popcorn and Basic cover most weak enemies that can be one shot with a well aimed critical hit or even just a standard attack. While these enemies will all have a type of “Basic” the formula for determining their Quick Kill Bonus might be classed as “Popcorn” because they are super weak and only have a small amount of health (ie Primal Thralls).
Elite
These guys are a bit tougher and have more health than your Basic tier. Enemies such as Evolved Thralls and Varelsi Hunters fall into this tier.
Champion
These guys are your proper tank types and may also sport a shield and other survival (trolling) tactics. Enemies such as Thrall Bonecrushers, MX. Elite Bots and Varelsi Defilers are tanks.
Boss/Unique
Those things that drop Legendaries (…well sometimes).
Note there are some other tiers, which cover things like environmental hazards and buildables, but for now we only care about stuff that generally don’t remain stationary.
Another thing to factor in is the mission difficulty and number of players. Internally there seems to be 4 difficulty settings, which I am not totally certain directly correspond to the difficulty options available in game…
- Easy (Normal Difficulty)
- Normal (Advanced Difficulty)
- Advanced
- Expert
So looking at a Primal Thrall:
Quick Kill Bonus Time Limit = PopcornGrade (0.25)
Quick Kill Bonus Score = GlobalScaleUpPerDifficulty(Difficulty * PercentPerDifficultyLevel) * PopcornBonusScore (0)
So even though you have 0.25 seconds, no matter how fast you kill a Primal Thrall, you won’t get any bonus score (regardless of difficulty) 
Note: I’m not sure if the Bonus Score is added to the Base Score or if it simply replaces it. Will have to check this next time I play.
There’s a ton of conditional logic involved with calculating stats on enemies so I’m still tweaking my code but here’s some base values you can use to get a general idea of how Quick Kill Bonus works with each tier. These are base values, so you will have more time (and get more bonus score) on higher difficulties and/or with more players.
Note: It is also possible that these values are outdated as I am more than certain that patches/updates are getting applied in a way were I can’t always see the changes. However I don’t believe they have touched any of these stats yet.
Edit: Added Advanced mode values.
Popcorn
BaseScore: 25 / 31.25
BaseQKBonusScore: 0
BaseQKTimeLimit: 0.25 seconds
Basic
BaseScore: 50 / 62.5
BaseQKBonusScore: 100 / 125
BaseQKTimeLimit: 1 second
Elite
BaseScore: 100 / 125
BaseQKBonusScore: 400 / 500 (that’s 4x!!)
BaseQKTimeLimit: 2 seconds
Champion
BaseScore: 500 / 625
BaseQKBonusScore: 2500 / 3125 (holy cow!!)
BaseQKTimeLimit: 8 seconds
Boss/Unique
BaseScore: 2000 / 2500
BaseQKBonusScore: 4500 / 5625
BaseQKTimeLimit: 25 seconds (how is that even possible??)
You’d definitely want snipers and/or loadouts/builds with shield penetration if you hope to get Quick Kill Bonus on middle tier enemies as most of them will sport a shield and can even have an anti-shield penetration stat to counter your builds!!
An important thing to keep in mind is that while you will have more time and get a higher bonus score with more players and higher difficulties, all of an enemy’s stats go up as well (health, shield, attack power, etc), making it harder to take them down especially since they will also spawn in greater numbers and tend to be more aggressive!
My thoughts on all this…the majority of public matches I end up in are more focused on reviving each other and/or dying (like a lot). I’m also in Australia so I have the benefit of an always-on red bar despite having the best possible wired connection I can get. While there’s definitely plenty of elite/champion enemies spawning in 5 player matches (they literally spawn so much that they stack like cards XD), the sweet spot has always been when you have a team of 2 or 3. Most missions require you to defend something that practically everything will b-line for, so it can definitely be challenging to get those Quick Kills in with everything else going on.
If you are seriously going for high score, I’d stick to private matches unless you are just in it for a quick boss run. Just sit back and pick off enemies one by one since completion time apparently plays no part in your final score. You also have a maximum of 100 minutes to stretch out a mission and find a boss that constantly spawns enemies to rack up your score (and just so you know, I didn’t learn this fact through data mining XD).
Don’t forget!! The quick kill bonus time limit activates the moment an enemy takes damage from any source!!
[edit]
Ok so I’ve been comparing values with what I’m seeing in-game and it looks like “Easy” is Normal difficulty and “Normal” is Advanced difficulty. The other 2 modes don’t seem to be used at the moment (maybe a future TVHM or just something they used for testing balance?).
If you kill a M1. Blade Bot on Normal, they give you 25 points, and on Advanced they are worth 31 (it’s actually 31.25 but is hidden due to rounding). Like Primal Thralls, Blade Bots are Popcorn grade so they don’t give you any bonus score for killing them fast. Playing in Hardcore doesn’t appear to play any part in the game difficulty used in these calculations.
Also Quick Kill Bonus Time Limit actually doesn’t appear to scale at all 
, and the Quick Kill Bonus Score is only affected by Game Difficulty. Having more players won’t increase the amount of bonus score you get from killing an enemy quickly, so the only benefit of having more players is an increased number in middle tier (Elite & Champion) enemies, which equals more score anyway.
Attack Power, Maximum Health and Maximum Shield Strength are affected by the number of players, but by the looks of it only in the internal"Advanced" and “Expert” modes which aren’t currently available in the game.. Correction I was only calculating values using NumPlayers=1.
[edit2]
So it looks like you can still get part of the Quick Kill Bonus even if you take longer than the time limit to kill an enemy. Basically the amount of bonus is added to the base score with an unknown (but high) rate of decay. I don’t know the actual formula, but say for example you are using Marquis and you have Auto Loader active. Landing 2 critical hits with Bindlebane’s sniper scope on an MX.Striker will kill them quick enough to get 67-70 score (which is +17-20 more that what you’d normally get) out of a possible 150. That’s quite a loss in bonus points but at least you aren’t getting totally ripped off!!
