The infected learn

The dead notice what the living keep doing to them. Not one survivor's habits: everyone's, across the whole county, over about a week. When one way of killing or fooling them gets used far more than anything else, they slowly start to answer it.

How you'll know

• You hear it first. Before they change, people outdoors hear humming far off, like a crowd holding one low note. It comes from the direction of wherever that trick is used most.
• Then it shows, a little at first and more over the next day. Watch how they move: every change has a sign you can see.
• The Haven station (88.1) calls it when a change starts to show, and a threat assessment is posted every Sunday evening on the terminals and in Discord #world-news.
• The first time you see a change, your Codex opens a page on it. See it a few more times and your notes start to say what works against it. If you're the first on the server to see one, your name goes on the page.

What to do about it

Every change has an answer, and nobody will tell you what it is. Watch, try things and write it down. They only ever answer the two tricks used most, and when people stop using a trick the answer fades within a couple of days.

Mixing it up is the best defense. A server that uses a bit of everything teaches them nothing.