Harpoon

Hold the button and the spear flies out on a chain, arcing downward as it travels, then comes back to you. There is almost no cooldown once it is home, so your real rate of fire is however long the round trip takes. Point blank shots return instantly and let you spam. Long shots across a room leave you empty handed for a moment. Letting go of the button pulls it back early, which is how you cut a bad shot short.

It damages on the way out and on the way home, and coming back it passes through blocks. Against a line of weak enemies, aim high and over the crowd rather than straight into the nearest one. The outbound spear stops after a few bodies, but the return sweep catches everything in the lane as it comes to you. The bleed it leaves behind adds up on anything that survives the pass.

It falls from the enemies of a Goblin Army, rarely enough that most players stumble into it rather than farm it. Get one early and it outclasses most bows you could have at that point for crowd work. The hardmode weapon that plays the same way is the Anchor, though that one counts as melee.