Giant Fungi Bulb

The bulb anchors to a block in glowing mushroom ground and stretches out on a stalk to reach you, the same trick a Man Eater or Snatcher pulls, except this one reaches much further and never has to touch you at all. It only appears once the world is in Hardmode, and it grows in mushroom patches on the surface as readily as in the caverns. Given a clear view of you it spits a Fungi Spore on a steady rhythm, and the spore is the dangerous half of the encounter. It hurts more than the plant does, and rather than flying straight it snakes downward on a wandering path, so backing away in open ground rarely shakes it off.

It alternates between a resting reach and a much longer one, holding the short version for several seconds before briefly stretching out. Measuring your safe distance once and trusting it is how people get caught, because the gap you paced out was the short reach. Cover is the real answer. It will not fire without a clear line to you, and its spores break apart on the first block they touch, so a single layer of dirt between you and the plant absorbs everything it throws. When one is heckling you from across a cavern, digging your tunnel a row lower usually ends the argument, and a bulb walled in behind blocks can be ignored completely.

Spores die to one hit from anything, tools included, so a wide swing clears the air in front of you. The better trick is hitting the bulb itself, since any damage restarts its attack timer. Keep steady fire on it and it spends the whole fight winding up without ever shooting, which makes fast weapons far better here than slow heavy ones. Do not bother trying to drown it in lava, because like everything that passes through terrain it swims through the stuff untouched. In Expert the spores move much more erratically on the way in, so reading their path is a waste of effort. Shoot them down instead of trying to dodge.