Allows you to gain experience upon killing an enemy (you can disable it if you only want to have cosmetic effects).
You gain 10XP on kill, the experience amount is multiplied depending on which difficulty you play:
Normal - x1
Hard - x1
Very Hard - x1.1
Overkill - x1.5
Mayhem - x2
Death Wish - x2.8
Death Sentence - x3.5
Killing special cops (and bosses) grants you 20% more XP and makes all the other cops give you 20% more XP for the next 10 seconds. (Does not stack)
There is a soft cap that will reduce the amount of xp gained per kill progressively as the total xp earned gets higher above threshold (on current level)
Thresholds:
Normal - 1000XP
Hard - 1100XP
Very Hard - 1100XP
Overkill - 2000XP
Mayhem - 3000XP
Death Wish - 4000XP
Death Sentence - 5000XP
The visual effects were heavily inspired by those that appear in CoD but due to how difficulty is it to make it look good in payday 2 its not perfect. Multi kill texts appear whenever you kill more than 1 enemy within 5 second time period (based on experience text duration).