Pathblaster

From Teletraan I: The Transformers Wiki

An enormous Decepticon weapon. In development during the Time Wars, it was being stored on the shuttle used by the Wreckers and the Mayhem Attack Squad. After destroying a chunk of Galvatron's head (a considerable feat, bearing in mind how much this guy has been shot by now), the gun explodes in Roadbuster's hands. The Pathblaster, Roadbuster, and half of Galvatron's face are never seen again. Although only shown a handful of times, it was this intervention that gave Galvatron the last little step into insanity.