Nice :)
I was thinking of it all more as the demons attacking *before* the marine's counter-attack, or the last demons on the near-earth outposts holding their ground against "normal" marines.
Yeah, not very special, but that's how I pictured it, and still think it should be implemented.
Anyway, IMO, "One achieved Hell Knight rank before being killed" sounds better, as he ain't an Imp any longer, and deserves recognition :P, and:
Before him 17 other Imps failed to build an empire, on a fools quest to rule hell.
Beside them 8 Hell Knights were brought to their knees, taking with them more than others could.
Others witnessed 3 Barons of Hell as they rised most violently,
and proceeded to scorch the earth as they burnt out.
Throughout it all, though, the Cyberdemon has been killed 2 times.
Despair, mortals, for he will never truely die.
sounds to me even better.
The idea is that those who reached a certain rank were destined to or were it, and, furthermore, the idea behind the Cyberdemon line is that he's possibly reincarnated, and not resurrected or rebuilt, and only his corrupt soul could possibly survive the path to Hell's Kingship!
Naturally, each line makes the dead dude look better, considering the ~feudal system :P