I am not a contributor to this mod, or anything else but I'm getting irritated by the people commenting on this.

1. Normal campaigns work 99% of the time as it erases all of the already existing infected that will come out.

2. The only exception is, that the ones that come out when 'scripted' so in events that the zombies that don't naturally appear, but are spawned manually. For example, there is a timer on a custom map that makes zombies every few seconds. In those cases this mutation will not stop that.

3. Special infected, are all 1 shot killed (few exceptions on custom maps)

4. Everything above is already said so in the description. Hell, I practice naviating with this mutation or try out how the map will happen on single player.

5. If all of the infected are one-hit kills and you're still complaining they hurt you, seriously, try aiming better. If you can't shoot a melee enemy that is running at you in plain sight and get a hit from it, where are you even looking, the sky?