The KO Cannon is a Hardmode melee weapon which is rarely dropped by any enemy or NPC during a Blood Moon in Hardmode, having a 1/1000 (0.1%) chance to drop. It autofires a boxing glove projectile that is connected to the weapon's base by a short, thick chain. After striking a target or traveling 17 blocks, the glove retracts back into the weapon before being ready to fire again.
Despite this weapon having a relatively short range compared to the Harpoon, its higher knockback, base damage, and immunity to gravitational arcing defines this weapon as an undisputed upgrade to the Harpoon.
The KO Cannon has no cooldown period; therefore its autofire rate is dependent only on the distance to its impact, meaning that an enemy or object in close range will cause a faster autofire rate.
- Although not able to strike multiple targets simultaneously, its rate of fire increases significantly when at closer ranges. Therefore, the player will find fending off hordes of enemies easier once they begin to close in due to its high knockback.
- One of the easiest ways to obtain this item is to set up multiple Bunny Statues or Fish Statues connected to a 1 Second Timer. During the Blood Moon event, activate the timer and kill all spawned Bunnies. It is easiest to do this with a penetrating weapon, such as a Laser Rifle or any gun using Meteor Shot rounds. Another easy method is to use the Spiky Balls from the Goblin Tinkerer.
- If aimed to the left, the "KO" on its side will be mirrored.
- "KO" is an abbreviation of "knockout", a term originally used in boxing, which is also referenced by the boxing glove being fired.
- The KO cannon has a very high speed when close to enemies due to the amount of time it takes for the glove to come back to the base as well as high damage. This makes it useful for defeating enemies such as the Paladin.
- 电脑版 188.8.131.52：Item and projectile sprites updated.
- 电脑版 184.108.40.206：
- Damage increased from 35 to 40.
- Fixed a bug where the KO Cannon could drop from statue-spawned enemies.
- 电脑版 1.2：引入。
- 主机版 1.02：引入。
- 移动版 1.2.6508：引入。