Transformers: Prime S02E07 - Crossfire

Megatron sends Breakdown, Airachnid and Dreadwing in search of energon in a forest, with Airachnid unaware that her comrades have actually been ordered to terminate her for treason. She catches on to the plan and flees, killing Breakdown in the process, and upon encountering a lone Insecticon, she uses her abilities to control it, and challenges Megatron to a fight to the death, but not before having it attack Starscream. Starscream passes on the Insecticon's presence on Earth, leading to the Autobots becoming involved and another face-off between Arcee and Airachnid.

Deaths: Breakdown