In the Black Library book, Aurelian, we learn of Lorgar's journey and (very willing) fall to chaos as the only true deities worthy of his worship.
Told as a tale that flicks back and forth between the past and present, Lorgar has a candid exchange with Magnus. In doing so, he informs Magnus of all the preceding events that lead him up to the position that he is currently in. This includes a tour with Ingethel of various future realities - some are going to turn out to be true, but others are not (Argel Tal's death for instance). Lorgar is tested by the gods, including Khorne who sends his champion to take his skull as part of the test.
The pacing of the novella is good and includes many action scenes surrounding Lorgar and how his whole demeanour and attitude has changed in the present - so much so that even Horus has become somewhat wary of him.
On the negative side, I didn't care much for how Khorne was reported to break the "pact" - there were no consequences for this ultimately, so how come Khorne broke it and Slaanesh, Tzeentch and Nurgle thought that that was all okay? Could the others have teamed up and said "Oi, Khorne! I really respect your rage, but leave Lorgar alone - he's like totally critical to all our plans so don't stuff it all up!".
The audio book of Aurelian contains voice acting by the reader. Most of it is good, but the one character that really irritated me was Fateweaver. His audio characterisation and lines might as well have been right out of Dungeons and Dragons at its worst. He lies, or does he? He tells the truth now. But never again. Or does he? At least Angron's advice that everything bleeds can be well heeded, even if Angron's characterisation of distilled rage was somewhat weak (perhaps he had a clear head day for once?).
Overall, I'd happily give Aurelian 3 stars out of 5 - a very enjoyable novella if one ignores some of the lines and allows the action and deep backstory to wash over!