Complex sentence: The Terrorocons combined into Abominus and to combat him Grimlock transferred his vast intellect into Computron, the Technobots' combined form, leaving him in the same mental state as before.
Split into simpler sentences: The Terrorocons combined into Abominus and to combat him, Grimlock transferred his vast intellect into Computron, the Technobots' combined form. This left Grimlock in the same mental state as before.