What sort of good stuff can a Knight of Doom serve to others? Serve order or some sort of obligations, or maybe some oathes and pledges. Or may be such knight can serve technology (and maybe some systems). Or self-sacrifice? I don't know, really. What's your opinion or theories?

As per usual, Serving Doom to enemies is technically serving others through Doom, so that’s serving help and good stuff in a roundabout way? I do know what you mean, though, and… Outside of literally Serving others Through Doom, I can’t quite think of any too-positive way to Serve Doom to someone in a positive manner. I’d say oathes or pledges would be more Blood-based- But obligations? A Knight of Doom working as a supervisor and trying to get others to get shit done? I like that.