Complex sentence: Suddenly the soldier who was telling the joke runs back, saying he remembers the end of the joke; before he can finish his sentence, however, a bullet shoots out his forehead and an ambush on Kraken's unit ensues.
Split into simpler sentences: Suddenly the soldier who was telling the joke runs back, saying he remembers the end of the joke. Before he can finish his sentence, however, a bullet shoots out his forehead and an ambush on Kraken's unit ensues.