If possible, spam Railguns to take down that Monolith fast. If he's taking both a Mono and the Nightbringer at 1500 pts he wont have much else, so bring the mono down and you've probably won. The Nightbringer is scary, but not particularly dangerous of you can tie him up far enough away from your important units.
Keep in mind that your Fire Warriors have a 6" longer range (3" for Rapid Fire) than his Warriors, so use that to your advantage. With both a Mono and Nightbringer, he will be in realistic risk of Phase Out
Keep in mind that your Fire Warriors have a 6" longer range (3" for Rapid Fire) than his Warriors, so use that to your advantage. With both a Mono and Nightbringer, he will be in realistic risk of Phase Out