Complex sentence: Sandra's anger at him frequently sets him on fire, though there is some speculation that his powers could block this but that he allows her to do so as penance and in order to vent her building demonic rage.
Split into simpler sentences: Sandra's anger at him frequently sets him on fire. There is some speculation that his powers could block this but that he allows her to do so as penance and in order to vent her building demonic rage.