Okay!! Wow! The "Does Not Render" set of lights is very cool. And there's a bit I don't understand. Shadows off makes sense, and diffused and specular set to black sounds intuitive, but what does it do where Color, set to white, is connected to a Simple Color node of black? It seems like that's got to be where the Major Magic happens and I obviously do not understand the consequences of that connection. Somehow that makes it shine white in preview and black when rendered?

Back to Blackbody node. Are we talking physics? Are you creating a blackbody by, hmm, maybe setting intensity negative? Something else? And how does it help? Wanna play with it and see for myself!