KF2 Afflictions Explained: Stun, Stumble, Freeze, Cooldowns

Afflictions are temporary states in which a Zed's normal behavior is impaired, effectively the debuffs of KF2. This reference, an appendix of Tamari's KF2 Survival Handbook (see the handbook index), explains the terms, then goes through every affliction, the rules for stacking and immunity, and the per-Zed and per-weapon numbers (valid for KF2 v1081, Back and Kickin' Brass). For another numbers table see Zeds in numbers.

How afflictions work

Perk skills, weapons and attacks apply afflictions. How well a given source does this is its Affliction Power. The Affliction Threshold is how much power a Zed needs to take before the affliction triggers. If a single attack has more power than the threshold, the affliction applies. Otherwise the power is added to a running total that drains at the Affliction Dissipation Rate, so continued hits can still push the Zed over.

Example: the M14 EBR has a Stun Power of 15 per shot and the Crossbow 100. Against a Scrake with a stun threshold of 100 the M14 needs several quick shots while the Crossbow can usually stun with one.

A Scrake affected by several afflictions. From left to right: stun, freeze, burn, bleed.

The afflictions

• Knockdown: Zed falls to the ground in a ragdoll state, fully incapacitated briefly. Caused by explosives, ballistic damage and mechanics such as goomba stomping.
• Stun: immobilizes the Zed so it cannot act for a short time. Caused by high burst damage weapons (Rail Gun, M99), some grenades (Flashbang, Nail Bomb) and skills such as the Firebug's level 15 Zed Shrapnel.
• Stumble: the Zed staggers and loses balance, pausing its AI for a moment. Most grenades and ballistic damage do this. Skills like the Commando's Impact Rounds or Support's Concussion Rounds amplify stumble.
• Melee Hit / Gun Hit: a flinch, sometimes a stagger. Caused by melee weapons or bullets, and by bash cancelling.
• Snare: reduces movement speed for a short time. Mostly from freeze damage, plus skills such as SWAT's Cripple.
• Freeze: similar to stun. Comes from the Survivalist's Freezethrower and the Sharpshooter's Freeze Grenades.
• Bleed: makes the Zed more vulnerable to the power of other afflictions, attack 25% slower, move 30% slower and deal 30% less damage. At the time of writing only the Field Medic's Hemogoblin applies it.
• Panic: the Zed runs around randomly and neither pursues nor attacks. Caused by burning, electric, poison and microwave damage. Electric damage (certain traps, the Berserker's EMP Grenade, Killerwatt) also calms enraged Zeds.

Precedence

When several afflictions are stacked, the game uses this order, highest first: Knockdown, Stun, Stumble, Freeze, Snare, Melee Hit, Gun Hit, Electric, Burn, Poison, Microwave, Bleed. The last four electric, burn, poison and microwave are the panic group.

Immunity and cooldown

After an affliction triggers, the Zed goes on Affliction Cooldown and cannot be afflicted again until it ends, unless the new affliction has higher precedence. Example: a burning, panicking Scrake can still be frozen, because freeze outranks panic. The cooldown applies to all players regardless of who started it, cannot be shortened, and differs by affliction and Zed.

This is why spamming Flashbangs at a Scrake does nothing. A Flashbang can deliver up to 400 stun power at the feet (explosives scale with proximity), far above the Scrake's threshold of 100, so power is not the problem. The Scrake has a 5 second stun cooldown. Even a teammate's Rail Gun headshot starts the same cooldown. Only a higher precedence affliction like knockdown can land during it.

Other special immunities:

• Zeds with any panic affliction are immune to stumble, melee hit and gun hit.
• Blocking Zeds are immune to knockdown, stun, stumble and freeze, and all other afflictions are 80% weaker.

Zeds performing a block.

Zeds that block: Gorefasts, Gorefiends, Bloats, Scrakes, Quarter Pounds, Fleshpounds and bosses. On higher difficulties they block more aggressively. Bait the block with small arms first, then throw your grenade, and ideally wait if teammates are about to fire at a Large Zed so you do not waste a Flashbang or Freeze Grenade.

Vulnerability

Vulnerability is a multiplier on incoming affliction power by Zed and hit zone, not on damage. A weak point, usually the head, has the highest value. Examples: a Bloat has 40% stumble vulnerability on all parts, so the M16 (stumble power 10) applies only 4. A Crawler has 200%, so the same shot applies 20. Skills modify power before vulnerability: Impact Rounds raises the M16 to 25 per bullet. Blocking applies its 80% reduction after everything else.

The formula for the raw affliction power dealt to a Zed.

Large Zeds and bosses have the lowest vulnerabilities and long cooldowns, which makes them very resistant overall.

Base values

Common to all Zeds and bosses: thresholds are 25 for electric, 65 for bleed and 100 for everything else. Dissipation is 50 per second for electric, 10 per second for poison and burning, and 20 per second for the rest. Bosses are fully immune to the panic effect of poison, though not to poison damage itself.

The guide gives a chart per Zed group: Cyst, Alpha Clot, Slasher and Rioter; Bloat; Crawler and Elite Crawler; Gorefast and Gorefiend; Stalker; Husk; E.D.A.R.; Siren; Scrake; Fleshpound and Quarter Pound; Dr. Hans Volter and the Patriarch; King Fleshpound; and Abomination and Krampus.

Affliction values for the Scrake.

Affliction values for the Fleshpound and Quarter Pound.

Weapon values

A second set of charts lists each weapon's affliction power, grouped as pistols, shotguns, SMGs, assault rifles, rifles, explosives, miscellaneous (Freezethrower, Killerwatt), flame weapons, melee, knives and hand grenades. Different fire modes are labeled in brackets. Pistol values cover single and akimbo. Example: the M16 M203 applies 10 stumble per bullet, 400 on a direct grenade hit and 1 to 400 from the blast depending on distance.

Affliction values for the M16 M203 Assault Rifle.

Per-skill and per-weapon combinations are too many to cover, so treat the charts as a reference rather than a complete list. The art in the original is by littletino.