Complex sentence: Tornado, who is no longer a match for Grundy's superhuman strength, is beaten and mutilated by the undead brute and through sheer force of will is able to summon winds that snap the immortal monster like a tree.
Split into simpler sentences: Tornado, who is no longer a match for Grundy's superhuman strength, is beaten and mutilated by the undead brute. In spite of his severe injuries, through sheer force of will he is able to summon winds that snap the immortal monster like a tree.