Venom Dart Trap

No world generates one, so every Venom Dart Trap in your world is something you sat down at a Mythril Anvil and made. That is a different mindset from the plain Dart Trap, which you pry out of a cave and reuse. Plan where it goes before you spend the bars.

The dart passes through one solid block directly ahead of it, so you can bury the trap behind a wall face and leave nothing visible except the tile it fires past. A hammer turns it to face the direction you want. In a corridor build that means the whole mechanism can sit inside the wall with only a single suspicious block on the surface.

The venom does most of the work, and it hurts players far more than it hurts monsters. As a mob grinder it is slow. As a defense for a base entrance, a trap hall, or anything aimed at other players, it is one of the meanest single tiles you can place, and the cooldown between shots is long enough that you should build them in banks rather than one at a time.