Denton Vanda Denton 
Vinctalin Legacy: Retaliation, Book 6 the Veekeren Element [EPUB ebook] 

The glorious Emperor, ex-slave to the Vinctalin, could prove to be their one enemy capable of destroying them. And he does not think small. Believing he has the means to save humanity, to say nothing of wreaking vengeance on his evil tormentors, Pakow Lam Fellen leads an attack on the Vinctalin Home World. Only the raving, traumatised psychiatrist can see the flaw in his plan, because only he has come to understand the nature of the beasts. The retaliatory strike on the Vinctalin increases hugely in complexity and scale, and horror, as a simple surgical strike turns into a mass attack on a number of solar systems.