The shots of the Rainbow Gun arc down, which makes it great for farming at certain spots in the dungeon. It also is a good extra damage addition during boss fights, especially for bosses that have a "fixed" height like Plantera outside of the Underground Jungle or the Golem. It is also very effective on a Blood Moon, Goblin Army, Solar Eclipse, and Pirate Army. The smaller the mob entrance on your location, the more effective this weapon becomes.
The gun can kill segmented enemies such as the Eater of Worlds, Destroyer, and Wyvern with very little effort (provided the player can make these enemies form a line to maximize the weapon's effect; it is advised that the player has a good amount of HP and armor when trying this).
Rainbow Gun is effective in PVP as it can be used for spawn camping and multi-hits, though it may disappear after the invincibilty of the player's respawn is gone.
- Sometimes the beam will pass through the target and not inflict damage. This seems to be more common with enemies that are standing still.
- If the player is aiming down on a 1 block wide layer of blocks, the beam will pass through.
- Similar to the above bullet point, If a player fires the gun through a two block thick slope from either side, the rainbow will pass through and, depending on the angle, pass through another 1 block thick wall.
- Added to the game.