Complex sentence: Raziel informed Dumah that he was going to kill him, and Dumah stated that he was even more powerful than Kain, after a heated battle that progressed throughout Dumah's keep, Raziel lead Dumah into a furnace, where Raziel set him ablaze.
Split into simpler sentences: Raziel informed Dumah that he was going to kill him, and Dumah stated that he was even more powerful than Kain. After a heated battle that progressed throughout Dumah's keep, Raziel lead Dumah into a furnace, where Raziel set him ablaze.