House of M

House Of M is the big Marvel crossover that has it's own series and plenty of mini-series leading off from it. It continues on from the Avengers: Dissasembled event from last year and will make big changes to the Marvel Universe. One of the confirmed changes will be 'Decimation' where most of the mutants are wiped out. It's average, I would say consider something else but this is a crossover so you'll probably have to get it to understand future stories.