Following the huge extended arc in War of Kings, this story begins with an alternate reality version of the Guardians of the Galaxy. I’m not tagging them because they appear only in issue #18.
They are joined by the actual Guardians team (i.e., the one that is ALSO from a possible future but one that is thoroughly enmeshed with Earth 616 and, therefore, are considered canonical for the purposes of this site). The Guardians were teleported into this future because they’re slipping in and out of realities, adrift in time after the destruction of the possible future they were in the last time we saw them.
Have I mentioned how annoying I find Time Travel to be?
In issue #18, they jump again and end up in a reality controlled by Magus and the Universal Church of Truth. Turns out that Kang is the puppeteer here–he wants to stop the creation of Magus.
After a few pages in this future, Kang sends the Guardians back to their own time, where they rejoin the rest of their team just before Phyla Vell can assassinate Adam Warlock to prevent him from becoming Magus.
Star-Lord has a Cosmic Cube from the alternate future and tries to use it to prevent Adam from turning–but it’s too late.
In the big Magus fight, the villain seemingly kills Phyla Vell (who somewhere along the way adopted the ironic codename “Martyr”)…
… as well as Mantis, Gamora, and Vance Astro. Then Magus is killed and this story ends.
All of these deaths are temporary.
The next issues are part of the “Realm of Kings” event. This series is mostly just a whole bunch of tie-ins. It’s still a solid read, but the continuity parts of it can be a little demanding for the reader.
English (US) · 