A Necklace of Water by Cate Tiernan

Following the unsuccessful magical rite, the Trieze is still discovering the implications. Thais and Clio begin to pursue separate agendas in terms of Deadalus- Thais wants to seek revenge for her father's death, while Clio seeks the immortality of the Trieze. A disappointing end to the series. A lot of things were left unfinished.