Snowman Cannon

You fire in the general direction and the rockets steer in themselves. That holds up against fast erratic targets and against segmented worms, where lining up manual shots is the whole problem. It also does no damage to you, so you can fire into something standing on top of you, which no other launcher at this level allows.

It is the strongest launcher that still respects rocket variants. Load liquid rockets and it becomes the quickest way in the game to place or clear water and lava from a distance, with no self damage to manage. Cluster rockets handle the fights. That range of jobs keeps it in the inventory long after better weapons show up.

The Ice Queen drops it, and the chance climbs with how deep into the Frost Moon you are. A run that stalls out on early waves is not going to produce one, so build the arena and the damage to push far first. Despite the name, it has nothing to do with the Snowball Cannon.