Complex sentence: Mastermind later died of the Legacy Virus, but before he succumbed, he asked Jean Grey's forgiveness for what he had done to her, she did forgive him, and he died at peace.
Split into simpler sentences: Mastermind later died of the Legacy Virus, but before he succumbed, he asked Jean Grey's forgiveness for what he had done to her. She did forgive him, and he died at peace.