Red Unicorn

Felling neglectd because her sorceress mother is enamored with a flamboyant magician and her sister, Empress Lizra, is infatuated with her own true love, Tanaquil is drawn into another world in which her mirror self is plotting to murder her sister.
SUMMARY:
The enchanting, magical sequel to The Black Unicorn and The Gold Unicorn!After several years traveling, Tanaquil — a sorceress like her mother with the ability to mend — returns home only to discover that her true love has been betrothed to her sister, Empress Lizra. Broken-hearted and jealous of her sister’s happiness, Tanaquil is lured by a red unicorn into a mirror world where she encounters Tanakil, a diabolical version of herself. She discovers also several new powers. Powers she will need to foil Tanakil’s sinister plot of revenge.