Defeasance of The Dark — John Willett

For ages, Isora's people have waged war against the demons of the dark. Now, with the annihilation of her species all but inevitable, she's sent across the cosmos to find the last of an ancient bloodline, a line forsworn to answer her call. Alone, the last of her kind in a strange and foreign world, will she find this being in time? Will they be able to turn the tide?