The Ray of Doom has a pierce of 100, popping bloons every frame (about 30 times per sec on good devices); 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 researching the Ray of Doom requires the Crystal Fusion Array. It costs File:City cash.png90000 and requires Phase Crystal Terrain. It takes 120 hours to research, costs File:City cash.png100000 for the upgrade, and requires File:BloonstoneIcon.png50.