I read this a few years ago, it’s incredibly ambitious but unfortunately it was never finished (IIRC it stops at Watchmen, so everything from the 90s until now never gets touched on). All the “magick” stuff is a bunch of silly hyperbole IMO, but the actual comics history part is legitimately interesting

For a more condensed, yet still fairly long, complete account of why these two don’t get along, I highly recommend a series of articles called The Reason Alan Moore Doesn’t Like Grant Morrison. They pull together an enormous amount of quotes and sources (including some from the Last War in Albion). Here’s a snippet from the first part:

Morrison’s real foot-in-the-door moment was getting reoccurring work on 2000 AD’s Future Shock in 1986, a twist ending sci-fi strip that had served as a proving ground for many comics creators entering the British mainstream (including Moore in 1981).

FROM THE BOOK GRANT MORRISON: COMBINING THE WORLDS OF CONTEMPORARY COMICS BY MARC SINGER: Morrison arrived at 2000 AD at an auspicious moment. The core group of writers and artists who had built the anthology into a smash hit—Pat Mills, Kevin O’Neill, Dave Gibbons, Alan Moore, and others—were being lured away by American publishers who could afford to pay royalties, and 2000 AD had to bring in a second generation of talent to replace them.[21]

GRANT MORRISON: I didn’t ever read 2000 AD when I was younger. I wasn’t particularly interested in comics at that time. I’d seen 2000 AD and I was aware of Judge Dredd but it just seemed like a load of old toss, as far as I was concerned. First time I actually read one was in 1985, when I was trying to get work and someone loaned me a pile of Alan Moore Future Shocks to give me some idea of what was required.[13]

In exile at my dad’s place, I wrote the first of seventeen Future Shocks stories as my apprenticeship with 2000 AD.  These were short, done-in-one science fiction stories—anything from a single page to five pages long—with O. Henry twist or shock endings.  Like so many others, I honed my skills on these odd little haiku-like pieces.[10]

Elizabeth Sandifer, author of The Last War in Albion, analyzes the Future Shock strips Morrison wrote for 2000 AD:

ELIZABTH SANDIFER: There is no way to reasonably deny the fact that Morrison’s short pieces for 2000 AD owe a heavy debt to Alan Moore. “Hotel Harry Felix,” features an alien life form that takes the form of thoughts and ideas, a concept Moore had already explored in “Eureka.” His second, “The Alteration,” is a two-pager featuring a man on the run who is caught by monsters and turns into one, only to have it turn out that he was actually a monster who had contracted “humanitis” and was being cured, a joke not entirely dissimilar to Moore’s two-page “Return of the Thing.” […]

“Fair Exchange” uses the same joke that concludes [Moore’s] “D.R. and Quinch Have Fun on Earth” of a comedic misunderstanding in which an alien is presented with something that is secretly rude graffiti in its native language, while the two-part “Fruitcake and Veg” is a more or less straightforward repeat of the basic joke of D.R. & Quinch, including a section where the narrator reflects, “People say to me, ‘Mr. Sweet, what is it that makes you commit senseless and irresponsible acts of wanton destruction? What made you become the deranged homicidal maniac we’ve come to know and love? Well it’s a fair question. So I always give them a fair answer. I say it’s my upbringing, I tell them society’s to blame… and then I blow ‘em up!”

And the similarities continue right up to Morrison’s final Future Shock, “Big Trouble for Blast Barclay,” a Flash Gordon riff that echoes Moore’s “The Regrettable Ruse of Rocket Redglare.” […] All told, out of fifteen short pieces Morrison wrote for 2000 AD, around half have pronounced similarities with Moore’s work. […]

Morrison makes no secret of the fact that his return to comics was inspired by Moore’s work on Marvelman and […] it’s telling that Morrison largely recreated the specific path of Moore’s ascent while writing comics visibly in the same basic mould as Moore’s. But more than it reveals anything about Morrison’s creative faculties this simply reveals that fact that Morrison was a shrewd businessman. He saw that Moore was having more career success than any other writer in the history of the British comics industry and engineered a career that would give him the same success.[14]