WRITERS: CHRIS CLAREMONT, LOUISE SIMONSON
ARTISTS: JIM LEE, ROB LIEFIELD, JON BOGDANOVE
This is it, the progenitor, the prototype, the big daddy - the first real mutant crossover, the harbinger of "X-Cutioner's Song", "Fatal Attractions", "Age of Apocalypse" and "Onslaught". Marvel's mutant titles had done events before, starting with "Fall of the Mutants" in 1988 and "Inferno" the following year but for those each title had remained relatively self-contained. But 1990's "X-Tinction Agenda" featured a full flow of three issues of the three books with a constantly shifting cast; if you didn't buy all nine issues involved you would not have a clue what was happening and while each title would subtly focus ever so slightly on the home team it was only as part of an ongoing plot.
