This collection has arguably the best issue of "X-Men Unlimited" ever: #10, in which the Age of Apocalypse-displaced Dark Beast disguises himself as his mainline counterpart, learns as much about the original Beast as possible, kills people along the way (in some cases as part of sick experiments) and eventually abducts and replaces the real McCoy (pun intended.) Shocking and disturbing, this is without a doubt the best X-Men comic Mark Waid wrote during his short time with the property. Watching as Dark Beast slowly but surely bricks Hank behind a wall is chilling, and the top moment that decade for both characters.
We also get a look at Onslaught's first henchman, the latest overpowered flavour-of-the-week 90's character: Post. Well, to call Post the flavour of the week is giving him too much credit. At least people cared about the likes of Exodus for a few issues. The X-Men exhaust themselves defeating the walking tank and - in a twist ending - there's warning that Post is but the "lowest of Onslaught's emissaries." Ugh. Not only is that horribly cliche, it also ends up being an empty threat: Onslaught's other "emissaries" were revealed to be Holocaust and... well, that's it. The Hulk is mind-controlled for a bit. Does that count? In retrospect, this was a warning sign that there were cracks in the grand Onslaught plan. Makes for some good Andy Kubert action scenes, though.
The rest of the volume is mainly filler including a Dr. Strange guest spot, a black-and-white Archangel comic and the X-Men's first encounter with Noseless Wolverine (MAN, that was a dumb idea.) There is a throw-in that is worth noting: the two part "X-Men: Brood" miniseries that ties up a loose end left by Chris Claremont years before. Written by John Ostrander and drawn by Bryan Hitch, it catches up with a woman who had been infected with a Brood egg and - up until then - hadn't been followed up with. It turns out she's been dragged around as a faith healer, and - in reality - has been infecting more people. When more Brood come to Earth to kill her, the X-Men stand in her defense. It's a good concept, well-executed and came as a pleasant surprise for me, as I had no idea this story existed.
That buried treasure makes me really glad these collections exist as printed. Yes, there is a lot of filler in the three volumes of "Prelude to Onslaught." But Marvel's dedication to getting, well... EVERYTHING X-Men out there unearthed a few gems, such as this and the Clandestine crossover that appeared in Volume 2. There are a lot of better X-Men collections out there, but if you're a completionist and are buying this anyway... gotta give credit to Marvel for going the extra mile. And even given the amount of throwaway stuff, and the fact that 90's over-saturation is in full force... these really aren't that bad. It was a pretty good time for Lobdell, though the company was about to run head first into a brick wall.