Complex sentence: A bunch of them were in Machinedramon's city working for him where when chasing Taichi Yagami, Agumon, Koushiro Izumi, and Tentomon, one collided it's attack with a Tankmon's destroying them.
Split into simpler sentences: A bunch of them were in Machinedramon's city working for him. When chasing Taichi Yagami, Agumon, Koushiro Izumi, and Tentomon, one collided its attack with a Tankmon's, destroying them.