Sounds like Mystique was pulling a Batman.
X-MEN CLASSIC OMNIBUS: When Classic X-Men first started, it consisted of reprints with new sequences added, plus all-new back-up features, originally by Chris Claremont and John Bolton. The omnibus reprints all of the new sequences and back-ups, plus other editorial changes, as well as the original and the new covers as well as pin-ups. Eventually, the new material and edits were dropped, but the reprints continued. In addition to including all the new covers, the omnibus also includes covers for other X-Men reprints series such as Amazing Adventures, X-Men: the Early Years and others.
X-Men Classic Omnibus is like a book of DVD deleted scenes. The thing is, most of the scenes deleted from movies were cut for a reason. In the case of Classic X-Men, the back-ups were added after the fact and are largely superfluous. Some of them (too few) are very good, but most of them are fat deserving of being trimmed. Reading them in conjunction with the originals as I have been doing is, frankly, distracting. Rather than adding depth, the new features, conversely, detract. If I ever read them again, it will be by themselves, and I may try to assemble them in strict chronological order. I really can recommend this omnibus to anyone who is not already very familiar with the originals, familiar enough to read the new material on its own and know what’s going on.
Wolverine's costume was coloured yellow on the original cover, but I think Byrne drew the new version, as the art has no shoulder-stripes.
I think the cover was the first appearance of the "Welcome... hope you survive" line.
Uncanny X-Men #139-140 and Machine Man #19 were the first time that I saw Alpha Flight though I did have #109 with Weapon Alpha.
Never saw them as a complete team until Alpha Flight #1 and then they were separated again!