Truffle

He is the only townsperson tied to a specific biome, and that biome does not exist until you make it. Glowing mushrooms spread on their own deep underground but never above ground, so the job is to haul mud up to the surface, plant mushroom grass on it, and let the glowing plants fill in until the game recognizes the patch. Around a hundred tiles of grass with plants growing on it is the working figure. The house itself is ordinary: walls, a door, light, a table and a chair.

Height is checked, and it is checked strictly. The room has to sit in the true surface or space layer, above sea level, which rules out the false surface a Remix world puts down in the caverns. The Mole people seed drops the height rule entirely, and there any mushroom biome at any depth will house him.

One more trap. The distance the game searches to decide a house counts as being in the biome is not the same distance it uses to decide the biome exists at all, so a room that looks buried in mushrooms can still be refused. When it fails you get a status message telling you the housing does not meet his requirements, with no hint about which half is wrong.

The fast way to grow the biome is the Clentaminator loaded with Dark Blue Solution, and he is the only person who sells that solution. The way out of the loop is that he arrives homeless the moment Hardmode starts, with no biome anywhere in the world and no house to his name, and the solution carries no unlock condition. Find the wandering Truffle, buy a stack, then spray a stretch of surface jungle and the mud turns over in seconds. Remix worlds usually drop the solution from his stock, so plan on planting by hand there.

Where he first sleeps decides where he can sleep later. If he spawns into an empty surface mushroom house on his own, he counts as unlocked, and from then on you can move him into any mushroom biome at any depth, including one you grew beside an underground farm. Walk a homeless Truffle into that same house by hand and he is not unlocked, and he stays chained to the surface.

The fix is blunt. Kill the Truffle currently in the world so the game has to place a fresh one, and let him find the house himself. The same split governs every later death: unlocked, he returns to any mushroom house at any height; not unlocked, only a surface one; and with neither available he simply comes back homeless again.

Housing goes to whoever is queued, not to whoever it was built for, so a brand new mushroom house is fair game for any NPC waiting on a vacancy. Finish spare rooms for everyone else before you finish his, or you spend an hour growing a biome and hand it to the Dye Trader. He is male, so a King Statue can also pull him around, which is occasionally quicker than rebuilding.

The Autohammer is the real reason anyone builds the mushroom house. It is the only machine that converts Chlorophyte into Shroomite, so every ranged character who wants that armor ends up here, and it does not appear on his counter until Plantera is down. The Mushroom Spear and Hammush open up earlier, after any mechanical boss dies, and both are respectable without being worth a detour on their own.

The pylon is the underrated line. A mushroom biome is somewhere you would otherwise never build, and once a second NPC lives nearby you can buy the node and stop making the walk. Hybrid biomes mean he can sell other pylons too, with the Forest and Cavern ones as the exceptions, since those two only appear when you are not standing in one of the named biomes. The Mushroom Cap and the My Son painting are decoration.

Threaten him and he does not just cower. He puts out spores that hang in midair and burst into clouds when an enemy touches them, and that spore attack does more damage per second than any other townsperson's defense. It will not carry him through a Solar Eclipse, but a mushroom house with him in it is less of a liability on a Blood Moon than you might expect.

• Every name he can be given is a mushroom or part of one, from Amanita and Morel through to Shiitake and Enoki. The odd one out is Leinspores, a pun on a former Re-Logic staffer plus the word spores.
• His eyes give off light in a dark room, and so does his cap.
• He is often mistaken for having a single eye. The figurine is to blame; the achievement art gives him two, and his Shimmer portrait leans into the joke by giving him exactly one while his attacking sprite keeps both.
• The Guide's hint about him suggests he grew out of an ordinary surface glowing mushroom, which goes some way toward explaining why half the town keeps trying to eat him or brew him.
• He is the only NPC who swings his arms at his sides while walking instead of holding them bent.