* ScheduleSlip: ''The Warmaster'' was originally scheduled to come out at the end of 2013, with a summary and cover art released in the spring and several tweets during the summer indicating that Abnett was working on it. Then it fell off the radar with no explanation until a December 2017 release date was announced.
* WhatCouldHaveBeen: Abnett has revealed that he lost the text of one of the books and had to rewrite it at short notice... and in the process invented the character of Lijah Cuu on the spur of the moment.
** There's an in-universe example in ''Blood Pact'', where Tona tells Gaunt that Slaydo's choice between Macaroth and him as succeeding Warmaster was essentially a toss-up and he could have been the new Warmaster. Gaunt tells her to perish the thought, pointing out that she wasn't there, and didn't know the Crusade's leadership or the internal politics... [[spoiler: until Gaunt meets Warmaster Macaroth a year or two later, and Macaroth himself points out that Gaunt nearly became the Warmaster instead of him.]]
* MeaningfulName: ''First and Only''. Abnett states in Black Library Classics reprint that he expected the book to be his first and last attempt at commissioned novel before heading back to comic book scene, but the series got off on its own.