Stake

Mourning Wood drops it during a Pumpkin Moon, with better odds the deeper into the night you get, so pushing to later waves pays off more than repeating the early ones. It arrives with a starter supply of Stakes, and after that both the Witch Doctor and the Arms Dealer will carry them, but only while the launcher is in your inventory. Fired stakes are gone for good, so there is nothing to sweep up after a fight.

The shots run flat and quick with no drop to compensate for, which makes this one of the easier weapons of its tier to aim. Each stake bores through a long line of enemies before it stops, though every body it crosses takes a bite out of what the next one receives, so the enemy at the back of a queue is hit far softer than the one at the front. Point it down the length of a worm and the whole thing lights up at once. Unreal is the modifier to aim for.

It sits in an odd spot in the bookkeeping. An Archery Potion, Shroomite armor and the Magic Quiver all treat it as a bow and improve it accordingly. At the same time the Rifle Scope reads it as a gun, so you get the zoom that bows never receive. Very little else in the game collects both sets of bonuses, and stacking them is what pushes it past weapons that look stronger written down.

Against Vampires it stops being a weapon and becomes an execution. The multiplier lands on the finished hit before their defense is taken off, so a Solar Eclipse full of them turns into cleanup work and it is worth carrying purely for that. The joke is the obvious one: folklore says a wooden stake is what reliably kills a vampire, and the game takes that at its word.