Complex sentence: The missile hits the Eiffel Tower and releases the nanomites in it, destroying the tower and some of the surrounding area before Duke manages to hit the kill switch, but in so doing, he is captured and taken to McCullen's base under the Arctic.
Split into simpler sentences: The missile hits the Eiffel Tower and releases the nanomites in it, destroying the tower and some of the surrounding area before Duke manages to hit the kill switch. However, in so doing, he is captured and taken to McCullen's base under the Arctic.