Complex sentence: In addition, during the Next Wave invasion of Night Mare, Irene succeeded her mother as Xanth's second-ever female King, and she used her power over plants to erect a massive arboreal defense perimeter around Castle Roogna.
Split into simpler sentences: In addition, during the Next Wave invasion of Night Mare, Irene succeeded her mother as Xanth's second female King in known history. She used her power over plants to erect a massive arboreal defense perimeter around Castle Roogna.