Shadow on the Stones [Guardians of the Tall Stones #3]

Shadow on the Stones is the third book of the Guardians of the Tall Stones series.
Kyra, priest of the Temple of the Sun, and her husband the Lord Khu-ren, have guided their civilisation to a time of spiritual strength, psychic energy, and communal peace. But there is a shadow on the Stones -- the spreading influence of the terrible god Groth, dark god of chaos and barbarity. Only the priests of the Temple possess the power to resist the tides of destruction...