In the first Killing Floor each Perk had specific tasks required to level up, and all tasks must be completed to reach the next level. Killing Floor 2 simplified this by instead just requiring each Perk to gain a certain amount of experience regardless of how they get it.
Every Perk has a primary XP objective and a secondary XP objective. The primary objective is always for killing zeds with the weapons of that Perk, while the secondary objective varies.
You can earn XP for one Perk while playing as a different Perk (for example, by playing as a Support with a Commando's Assault Rifle, or using the Medical Syringe to heal other players when not a Field Medic).
The Survivalist cannot earn XP for the primary objectives of other Perks (but can earn XP for the secondary objectives), and no other Perk can earn XP for the Survivalist unless they use the Freezethrower or Gore Shiv.
Each Perk has their own unique knife that they begin the match with. This knife only gets XP for that Perk. Unlike grenades, when you switch perks mid-match, you knife does not change. This is the only way to use the Gore Shiv as a perk other than the Survivalist.
When an enemy is killed, you get the full amount of XP that it is worth if you dealt damage to it, regardless of which player killed it. However, if you used weapons from multiple different Perks, then the XP is evenly split across those Perks regardless of how much damage each weapon did.
Some weapons count as a Perk Weapon for multiple Perks. These are called Cross-Perks.
Getting kills with the 9mm Pistol (or Dual 9mm Pistols) will always only give XP to your current perk.
Once a Perk reaches level 25, it is possible to Prestige and reset that Perk back to level zero for some rewards. Additionally, that Perk will gain 30% more XP to make leveling easier for it.
- Dealing Berserker weapon damage.
- Killing Zeds near a player with a Berserker weapon.
- Dealing Commando weapon damage.
- Killing stalkers with a Commando weapon
- Dealing Demolitionist weapon damage.
- Killing Fleshpounds with Demolitionist weapons
- Dealing Field Medic weapon damage.
- Healing Teammates.
- Dealing Firebug weapon damage.
- Killing Crawlers with Firebug weapons.
- Dealing Gunslinger weapon damage.
- Head shots with Gunslinger weapons.
- Dealing Sharpshooter weapon damage.
- Head shots with Sharpshooter weapons,
- Dealing Support weapon Damage.
- Welding doors.
- Dealing Damage with any weapon.
- Killing Clots with any weapon.
- Dealing SWAT weapon Damage.
- Killing Clots with SWAT weapons.