Well, that's a good start. Now that you have a solid base for an idea, you have to get into more details. You have to ask yourself why your band is slaying this daemon in particular? Is it vengeance for ruining your patrons god's plan, preventing the rival group from doing something the patron god won't like, or are your guys just being jerks and messing up the other group's plans just because they can.
If you're going to base it mostly off introducing the chapter, I have one big suggestion. Use flashbacks and actions to reveal traits of the characters, even dialogue going over the past. Justp please, please do not introduce a character, then go off for two paragraphs about them. That is the easy way to do it. Perhaps this is not the first time these two groups have met and as they fight, your protaganists are reminded of the first conflict. Maybe as they fight, your characters talk of other days such as ealier wars, past conflicts, even how your group hates its own members. Maybe as one of your characters is fighting, that daemon inside them starts talking to them, distracting them and going on about it views of the battle, and the warband in particular.
As Azriel said, check out the BL competition. This story seems to be shaping up.