Complex sentence: Magneto travels to his base on Asteroid M and calls the mutants of the world to join him on "The Mount", a portal to Asteroid M. Meanwhile the X-Men manage to free Xavier, and Xavier defeats Shadow King in a Gladiator-themed battle.
Split into simpler sentences: Magneto travels to his base on Asteroid M and calls the mutants of the world to join him on "The Mount". The X-Men manage to free Xavier, and Xavier defeats Shadow King in a Gladiator-themed battle.