Complex sentence: Her hand was forced by events instigated by Lady Death: with the disappearance of Lucifer, the Fallen Angels were moving on Hell in a bid to rule it--they attacked Necropolis first and Purgatori was forced to flee.
Split into simpler sentences: Her hand was forced by Lady Death: with the disappearance of Lucifer, the Fallen Angels were moving on Hell in a bid to rule it. They attacked Necropolis first and Purgatori was forced to flee.