Cursed Hammer

It picks a spot, hovers, spins itself up, then commits to one straight lunge that ignores every block in the way. The lunge is the only threat it has. Any knockback interrupts the spin and forces it to start over, so the enemy is either winding up or already past you, with nothing in between. Digging into a side pocket does not help, since it comes through the wall regardless. Never letting the wind up finish does.

Arkhalis and Terragrim reduce it to scenery. They keep a hitbox spinning around you at all times, so the hammer takes a knock every time it drifts close and never gets a charge away. Any fast weapon with knockback approximates that. Slow heavy swings are the wrong tool, because one miss hands it exactly the window it was waiting for.

It has spawn conditions attached that most enemies do not. Town NPCs anywhere near switch it off. Standing on a tile backed by safe background wall switches it off, which covers most built rooms. It also requires that you moved, jumped or used something within the last few seconds, so an idle character generates nothing at all. A Shadow Candle held or placed nearby waives the lot, and it is the difference between a corruption farm that runs and one that sits there empty. Worth knowing too that it only needs corrupt material beneath it, so ebonstone or purple ice that has spread into an old mine is enough, biome registration or not.

The Nazar is the draw. It blocks the same curse this enemy inflicts, and it feeds the Ankh Shield chain where every other component is an equally awkward hunt. These are rare by design, though a patch corrected them being far rarer than intended, so a current world produces them at a sane rate compared with older ones.

Of the three animated weapon enemies, this is the only one whose sprite is not recycled from a real item, though the handle looks borrowed from the enchanted sword family. It is also the only one of them that ever had a separate variant of its own.