Battle of the Atom has everything I like in an X-Men story. There are 40+ super powered characters that appear in this thing. There are multiple instances of time travel which result in at one point four different versions of Iceman at the same time. There are psychic battles and shapeshifters and for a book with three writers and six artists it is surprisingly coherent.
The plot in a nutshell is that X-Men from the future come back in time to tell the X-Men of the present that the X-Men from the past have to return to the past or the spacetime continuum will be destroyed, but more X-Men from the future arrive to say the first group of future X-men are lying. Oh, and the previous sentence contains spoilers.