Complex sentence: When Leslie learns that Irial is killing other mortals to keep her alive, Leslie takes Niall up on his offer and he uses sunlight and frost taken from the Winter and Summer Queens to burn and freeze the link and the tattoo off Leslie.
Split into simpler sentences: When Leslie learns that Irial is killing other mortals to keep her alive, she takes Niall up on his offer. He uses sunlight and frost taken from the Winter and Summer Queens to burn and freeze the link and the tattoo off Leslie.