Celebration

The Celebration is a rocket launcher dropped by the Moon Lord. It fires two rockets at once that travel a short distance before exploding. When the rockets detonate, they will have patterns and colors similar to fireworks. The best modifier is unreal.

Trivia
It doesn't have anything to do with MLP. The Celebration could be a reference to My Little Pony. One of the main characters, Pinkie Pie, owns a "party cannon" which has been shown in the series to possess offensive capabilities.