Complex sentence: The Invisible Woman's forcefield protects them for a few moments, but not long enough for Mister Fantastic to rescue them: he watches in horror as they are shredded by the forces of the Incursion.
Split into simpler sentences: The Invisible Woman's forcefield protects them for a few moments, but not long enough for Mister Fantastic to rescue them. He watches in horror as they are shredded by the forces of the Incursion.