BOOM! was, is, and will always be the mostly deadly weapon to ever be used in the history of history. It was used in the Videogame War by the Mushroom Kingdom to make sure Sony would have no chance of attacking the Mushroom Kingdom anymore. It is also responsible for over one hundred thousand deaths in Raccoon City. It even killed uh...you don't wanna know.
It appears as a water-like liquid, but it is actually a strong acid. It is thought to be just over twice as acidic as the old Teletubby Land Acid Lake. Upon reaction with Hyper Fireballs, however, it will detonate with the same force as a small thermonuclear bomb, or 20 megatons of Bomb-Omb filling.