Your first instinct: “This is an ear infection.” But no, it’s something worse, something terribly worse. It starts with an annoying itch, then follows a mild stinging sensation, and then comes the painful pounding from inside your head. The tainted moss crawler is a flying insect, usually found in the fungal wastes, but sometimes infected by a fungus, programmed to carry the infection to distant regions, where it must find a fitting host.
Adventurers who sleep in the wilderness, without shelter or proper ear protection, can easily become infected overnight. The bug slips into your ear, burrows further into the ear canal, tunnels its way through your skull, and starts feeding on your brain. After incubating for three to five days the first symptoms start to show up, and when the painful headache starts it is already too late. You have slowly turned into a mindless drone with only one program: serve the mother fungus.
You wander towards civilisation where you search for a populated place. Once there, you stop and wait, and wait, and wait. The mycelium grows inside of you and your flesh starts to wither, while the fungus nourishes on your soft internal tissue. While you are being eaten alive from inside, thousands of microscopic tendrils penetrate the skin of your feet and root you to the earth.
Eventually, the mushroom’s fruiting body sprouts from you, grows from your mouth, nose, eyes, and ears, rips apart your skin and splits your skull. If the townsfolk had ignored you up until now, it is too late for them as well. A new corner of the world was successfully conquered by the fungus that day, and as it releases its spores the villagers either run or they are doomed to experience the same fate as you.