Complex sentence: At the mines, Lugnut was about to use his punch on the Constructicons before Megatron showed up, Lugnut fell backward, activated his punch, and possibly destroying something in the process.
Split into simpler sentences: At the mines, Lugnut was about to use his punch on the Constructicons before Megatron showed up. Surprised, Lugnut fell backward, activated his punch, and possibly destroying something in the process.