Ray of Doom

"The Ray of Doom is a persistent solid beam of bloon destruction."

- Official Description

 is the final upgrade of Dartling Gun on Path 1, costing $46750 on Easy, $55000 on Medium, $59400 on Hard and $66000 on Impoppable. It allows the Dartling Gun to shoot a persistent beam that pops all bloons in its path.

The Ray of Doom has a pierce of 100, popping bloons every frame; even Ceramic Bloons are popped in well under a second. This upgrade is probably one of the best upgrades for popping normal Bloons, being a tower with one of the highest pierce caps in the entire game.

In Bloons Monkey City, the Ray of Doom requires the Crystal Fusion Array. It costs 90000 and requires Phase Crystal Terrain. It takes 120 hours to research, costs 100000 for the upgrade, and requires 50.

Trivia

 * Even though the description says that it shoots a persistent beam, it actually flashes, however this is purely cosmetic; the ray's area of effect is not affected by the flashing.
 * This upgrade might be a reference to the Star Wars movies, as the beam closely resembles a red lightsaber. This would also partially explain the flashing effect and when it's fired the dartling gun looks like a lightsaber handle.
 * This upgrade is notoriously bad against individual M.O.A.B. class bloons, as it has a popping pierce of 100 but only pops 1 layer per frame. This means it effectively loses 99% of its firepower. It is still more than a match for an individual M.O.A.B. or B.F.B. however, and indeed can take down large groups of them quickly. It only struggles against the mighty Z.O.M.G..
 * The Ray of Doom used to have infinite pierce. This was changed to 100 in an update. This was because it was over powered, being able to take out literally anything, even mass Z.O.M.Gs.
 * This upgrade has the same pierce as a 4-0 Juggernaut Dart Monkey.
 * The Ray of Doom can pop leads but the Laser Cannon cannot even though they appear to both be lasers.
 * The Ray of Doom negates the effects of upgrades in Path 2, but still needs Depleted Bloontonium Darts to pop leads in the mobile version.
 * The HAZMAT suit looks like the one for a Glue Splatter and Corrosive Glue Glue Gunner, but has a gas mask like the Bloon Dissolver and Bloon Liquefier Glue Gunner's. The color is also different.
 * This is the second most expensive upgrade in BTD5, after the Temple of the Monkey God.
 * The Ray of Doom will pierce through anything, but if it has reached its pop limit, it will still pierce through but not pop.
 * The Ray of Doom only stops shooting in between Rounds. It will constantly shoot the ray during rounds, even if there are no Bloons on screen. It will also constantly shoot in Sandbox Mode. However, with the Great Divide update, it no longer fires until a bloon exists.
 * This is one of the few lasers that can pop Lead Bloons. The others being High Energy Beacon, Bloonsday Device, 1/3 Robo-Monkey and Meerkat Spy Pro.
 * The Ray of Doom is very heavy, signified by slower movement with the mouse than a regular Dartling Gun.
 * The Ray of Doom causes relatively low lag compared to other late game towers (e.g. Temple Of The Monkey God) and might be a valid option to use in freeplay if your computer is slow
 * In Bloons Monkey City, it is said that this tower works with a Phase Crystal piece.
 * The gun itself could be a possible reference to the Sprtel-Wood 9700 from Fallout: New Vegas as both are gatling guns that shoot a long, continuous laser beam.
 * Ray of Doom beams are unaffected by Monkey Fort nor M.I.B Call to Arms in popping power.