Kindred by K.M. Raya

Princess Sera has lost everything.

After her castle is destroyed with her family inside, the realm rejoices the downfall of her father—the Tyrant King. Presumed dead, Sera flees to the one place nobody will ever find her—the Darklands.
For five years the princess trains in the kingdom of the Kindred—a haven for banished magical beings outlawed by the fallen king.
When a destructive new power rises and threatens her new home, Sera discoverers a dark, long hidden secret about herself that might help her save them all. A powerful ancient Dragon, a Warrior Elf and a renegade Necromancer from her past enlist themselves in Sera’s service—aiding her as she gathers the largest army of Kindred in history.
War is spilling into the Darklands and the last living royal will stop at nothing to save it.