Ruination : a league of legends novel / Anthony Reynolds.

Camavor is a brutal land with a bloody legacy. The Empire's knights go, slaughter follows. Kalista seeks to change that. When her young and narcissistic uncle Viego becomes king, she vows to temper his destructive instincts - as his loyal confidant, advisor and military general. But her plans are thwarted when an assassin's poisoned blade strikes Vigeo's wife Isolde, afflicting her with a malady for which there is no cure. As Isolde's condition worsens, Viego descends into madness and grief, threatening to drag Camavor down with him. Kalista makes a desperate gambit to save the kingdom: she searches for the long-lost Blessed Isles, rumoured to hold the queen's salvation if only Kalista can find them. But corruption grows in the Blessed Isles' capital, where a vengeful warden seeks to ensnare Kalista in his cruel machinations. She will be forced to choose between her loyalty to Viego and doing what she knows is right - for even in the face of utter darkness, one noble act can shine a light that saves the world.