Complex sentence: Nimrod later faces the combined forces of the X-Men and the Hellfire Club and proves himself as a powerful threat, killing Black Rook Friedrich Von Roehm, causing Harry Leland's fatal heart attack, nearly killing Nightcrawler and badly injuring Rogue and Sebastian Shaw.
Split into simpler sentences: Nimrod later faces the combined forces of the X-Men and the Hellfire Club. Nimrod proves himself a powerful threat, killing Black Rook Friedrich Von Roehm, causing Harry Leland's fatal heart attack, nearly killing Nightcrawler and badly injuring Rogue and Sebastian Shaw.