Harpoon

The harpoon is dropped by any goblin in the Goblin Army and acts like a flail, returning to the player after hitting a wall or enemy.

It fires a heavy projectile that falls quickly which is useful for trying to eliminate enemies on the other side of hills or similar areas. It also has a high knockback, making it effective as improvised home defense. The arc makes the Harpoon effectively similar to that of arrows fired from a bow, but with a slower re-fire rate and effectively infinite ammunition. Another upside to the harpoon is that it will continuously fire if the attack button is held down, unlike other flails.

In addition, its fire rate seems to be dependent on how long the harpoon itself is out of the weapon rather than being based on a set time, meaning while it will take a long time to reload after being fired a long distance, if it is fired close to the player it will refire quickly upon returning to the gun. This provides an effective way of juggling enemies against walls or along flat surfaces, as its low knockback allows it to rapidly and repeatedly strike enemies until they die.

Below is a video looking at the Harpoon: